HHO Electrolytes Explained

This article will answer several of the most common questions asked by those experimenting with HHO systems, HHO generators and specifically HHO Dry Cells. And also give you some safety measures to keep in place when experimenting with HHO gas production.

Why do I need Distilled water in my HHO generator?

Choice of what "grade" of water to use in a HHO generator:

Rainwater, spring water and tap water all contain impurities. A typical analysis will show minerals, suspended solids and other contaminates contained in these varieties. These impurities will precipitate out of the water when subjected to electrolysis. These appear in the form of brown, black and green scum in water or any discoloration of the water itself. These impurities have a solid mass which in turn will clog up the electrodes of your HHO generator and further impede the operation of the HHO cell overall. Of further concern is the fact that these solids accompany known gases which mix with the HHO gas and create unknown chemical reactions which are toxic to the environment, Therefore ONLY DISTILLED WATER SHOULD BE USED in the production of HHO gas from any type of HHO generator.


Exploded View of round HHO dry cell generator

Electrolyte and mixing:

There are many different electrolytes that CAN work in an electrolysis process, but does that mean they are suitable? NO.

Some common ones considered for HHO fuel making application include:

  • Potassium Hydroxide... KOH - Used in soap making

  • Sodium Hydroxide/ Lye... NaOH - Used to open drains

  • Sodium Chloride... NaCI - Table Salt- Raises blood pressure – DO NOT USE!

  • Baking Soda... NaHCO - Makes bubbles and poisonous gas – DO NOT USE!

  • Sulfuric Acid... H2SO4 - Car battery acid- Makes bad gases and burns! – DO NOT USE!

  • Vinegar... CH3CO2H - (5 to 10% solution of acetic acid) – DO NOT USE!

  • Sodium Sulfate... Na2SO4 – DO NOT USE!

There are many other electrolytes in the acid, base and salt families, but generally these are the common off the shelf ones considered for use in most HHO generators.


*Note first we need to understand what a catalyst is and how it works in our HHO Generator.

An electrolyte such as KOH acts as an ionizer for conduction of the electricity; whereas the nickel in stainless steel acts as the catalyst (hence the finish on the surface of the plates after iron is leached out). The better the flow of electricity the better the splitting of water to a point, current is the generator of heat. Once most of the free iron has been cleansed from the cells, the KOH or NaOH combines with the nickel (and molybdenum in 316L) to form the catalytic layers. The anode and cathode each take on a slightly different characteristic patina and chemistry.

By using distilled water it must be understood that this water cannot conduct enough electricity on its own, therefore a catalyst is required in order to aid electrolysis. The ideal catalyst is a substance that enables the reaction to take place without becoming a part of that reaction.

From empirical testing, it has been found that Potassium Hydroxide (KOH) and Sodium Hydroxide (NaOH) are two substances that catalyze efficiently. Tests have shown that when combining distilled water with one of these two catalysts that a cleaner HHO cell bath and more homogeneous HHO gas mix results. This results in a more efficiently operating HHO generator unit that improves mileage gains, performance and less emissions.

wireless amp meter for measuring HHO dry cell generator currentTherefore KOH is what you want to use. It is the most stable, and it is not consumed during the electrolysis. So once you have your HHO cell working at the target amperage you just need to add distilled water as the water is consumed, no more KOH. About once a month you want to use the water from your primary bubbler to replenish your HHO dry cell. This will put back any of the KOH that may have been carried by pressure or steam to your primary bubbler back into your cell.

Every couple of months you need to check your amp draw to confirm you haven't had any MAJOR Changes. About every 6 months it is a good idea to drain your HHO dry cell and refill with fresh electrolyte. This is because as you run your HHO generator it should get more efficient and require less KOH to get the same result.

Mixing KOH for your HHO Dry Cell:


Potassium hydroxide also known as "caustic potash" is highly caustic. This needs to be handled carefully and kept away from ANY contact with skin, and even more importantly your eyes. If any splashes come in contact with you, adding water on the affected area will cause it to react and heat up, the use of vinegar will neutralize the burning, then wash it off with allot of rinsing.

Always store it in a sturdy, air-tight container which is clearly labeled... DANGER! Potassium Hydroxide. Keep the container in a safe place where it can't be reached by children, pets or people who won't take any notice of the label. When working with dry KOH flakes or granules, wear safety goggles, rubber gloves, a long sleeved shirt, socks and long trousers. Additionally wear a face mask which covers your mouth and nose.

IF YOU ARE MIXING SOLID KOH WITH WATER, ALWAYS ADD THE KOH TO THE WATER, AND NOT THE OTHER WAY ROUND, and use a plastic container for the mixing, preferably one which has double the capacity of the finished mixture. The mixing should be done in a well-ventilated area which is not drafty as air currents can blow the dry KOH around.

WHEN MIXING THE ELECTROLYTE, NEVER USE WARM WATER. There results a chemical reaction between the water and the KOH which generates a lot of heat. Placing the mixing container in a larger container filled with cold water will help to keep the temperature down, and also prevent any spillage if your mixture should "boil over". Add only a small amount of KOH (table spoon) at a time, stirring continuously, and if you stop stirring for any reason, put the lids back on your storage container.

Electrolyte concentration DOES have a direct impact upon maximum obtainable efficiency of any type of HHO generator. If the electrolyte concentration is run at below peak conductivity, it is just like inserting resistance in series with a cell. Current flow is limited by the increased resistance of the solution. This causes less power to flow, BUT, more of the power that does flow is wasted as heat. Therefore, if one wishes to achieve peak efficiency with their HHO generator, and especially the HHO Dry Cell design, even at brute force DC, one would want to run the electrolyte concentration at peak conduction, and use another means to control current, such as a current regulator.

potassium-hydroxide KOH flakes for HHO dry cell generator electrolyteKOH is added into distilled water to bring conductivity. Without KOH / NaOH the current does not pass through the water from +Ve to -Ve. With the quantity of KOH / NaOH we control the current drawn by the HHO generator. That means if you add more KOH then more conductivity and less resistance hence more current and more gas production for applied voltage and vice versa. Hence the concentration of KOH is directly related to the current draw and the HHO gas production.

How much KOH Do I Mix For My HHO Dry Cell?

Auto-hydrogen recommends 3-5% KOH (or NaOH) electrolyte concentration (by weight) be used for optimal results in most situations. Other companies recommend concentration levels that are much higher but we find this to be unnecessary and increases the risk of chemical getting to your engine.

To mitigate freezing you can reduces the freeze point of the electrolyte by increasing the concentration to 10% and higher; but remember that because electrolyte is not consumed in the HHO electrolysis reaction, the concentration is actually double when the electrolyte water volume is decreased to one half the original volume. So with higher concentrations you must religiously maintain your electrolyte fluid level.

Adjust concentration based on amperage draw at startup of your HHO dry cell. Starting amperage limited by the electrolyte concentration should be 30-40% below the maximum current rating for the dry cell. This is close enough as during operation the dry cell heats up the electrolyte, and as the temperature of the electrolyte increases so does the current draw which should peak close to the maximum allowable for the dry cell.


  • To make 1 Kg of a 5% KOH solution by weight, add 50 grams of KOH to 950 cc of water.
  • To make 1 Kg of a 10% KOH solution by weight, add 100 grams of KOH to 900 cc of water.
  • To make 1 Kg of a 20% KOH solution by weight, add 200 grams of KOH to 800 cc of water.
  • To make 1 Kg of a 28% KOH solution by weight, add 280 grams of KOH to 720 cc of water.
  • The total weight is always 1,000 grams containing whatever percentage of KOH that is wanted.
Note for convenience: 50 grams of KOH (or NaOH) is approximately equivalent to ≈0.56 fluid ounces or ≈1.13 US tablespoons.


Your HHO Dry Cell and Electrolyte

Baking Soda for Water Fuel... a BIG NO

Using Baking Soda as an electrolyte to produce HHO gas:

stainless steel hho plate corroded by bad electrolyte baking soda and contaminationEmpirical tests have shown that using baking soda as an electrolyte gives a false sense of security. Baking soda will not only remain baking soda in use, but also cause permanent damage to the electrode surfaces in your HHO generator during its transition into sodium hydroxide.


Empirical tests have shown that after the gas was analyzed, there is hydrogen, some CO2, also enough CO to be lethal. There is NO oxygen produced until ALL of the carbon has been reacted from solution. It is not suitable to state that the gas produced is to be burned and not inhaled. Many "water fuel" experimenters who use baking soda are burning the gas when they are doing their experiments. Most are venting the gas into the air in the room they are in, and even those that DO burn the gas in an engine often-times have leaks in their Hydrogen on demand systems.

Baking soda will permanently damage the surface structure of stainless steel. That is why it has to be sanded or ground off, and then the cleansing and conditioning of your HHO dry cell started all over again.

Baking soda does not lose potency; it decomposes as a part of the reaction during electrolysis. Some carbon binds with the electrodes and causes damage to the surface structure, the rest of the carbon binds with oxygen to produce other products of reaction during electrolysis. While it is still baking soda, it does not produce HHO gas, it produces a blend of hydrogen (H2), carbon monoxide (CO), and carbon dioxide (CO2). As this occurs, the baking soda is transformed into NaOH, sodium hydroxide. This is why it keeps on working, but only as the carbon is consumed does it change into HHO gas.

A reliable and repeatable performance increase is not going to happen during the decomposition phase of baking soda. It will eventually stabilize, but not until all of the carbon is consumed.


BAKING SODA DECOMPOSES INTO NAOH DURING ELECTROLYSIS; you end up with a caustic material anyway. The worst part of this is, the end users are lulled into a false sense of security, thinking that it remains safe baking soda. So they are more prone to not take proper safety precautions. And if you are using expensive stainless steel electrodes in your HHO dry cell, they become damaged as the carbon will also poison the catalytic capabilities of stainless steel. Salt is also unsuitable as is battery acid. To recover the damage done to your HHO generator would require a real good sanding to get rid of the surface damage and start over.


Further you would have to add 84 grams of baking soda (NaHCO3) to obtain the same amount of sodium as you would for 40 grams of Sodium Hydroxide (NaOH). This is relevant because it is the Sodium that is driving the electrolysis process.

On electrolysis of NaHCO3, the Na+ ion will rush to the cathode and you will get:-

2Na+ + 2e- + 2H2O -----> 2NaOH + H2 and HCO3- + H2O -------> H2CO3 + OH-

Also   H2CO3 --------> H2O + CO2

Also   CO2 + 2H+ + 2e- -----> CO + H2O

Also   CO + 2H+ + 2e- ------> C + H2O


On adding NaHCO3 a whole range of chemical processes can take place but due to the nature of alkali metals, the one sure conclusion is that Hydroxides will be formed. DO NOT BE DECEIVED into thinking that if you make a completely safe electrolytic solution using NaHCO3 or other carbonates that you end up with a completely safe electrolytic solution after use. If one takes pH readings of the electrolytic solution over time, one can access the progress of the carbonate solution (pH will increase with increasing Alkalinity).

Using vinegar in HHO Generators:

A common person may reason that Vinegar (a 5 to 10% solution of acetic acid) is a suitable electrolyte for DC Electrolysis to make HHO Gas. Why not? It's cheap, sometimes cheaper then bottled water, everybody can buy it around the corner, and it is very safe you can drink it. WRONG.

dirty HHO stainless steel contaminated by vinegar electrolyte dc current over heatingIt's not a good electrolyte, and you can NOT count on its stability. One of the reasons is that it is not a solid with a high boiling point like the preferred KOH or NaOH, but pure Acetic Acid is a liquid, with a certain vapor pressure (you cannot smell cold KOH, while sniffing on a bottle of cold Acetic acid may let your nose fall off, it stinks pretty strong); and it has a boiling point not much higher than water.

(Water = 100°C, Acetic Acid = 118°C). And because many HHO Cells and HHO Hydrogen Boosters are run on elevated temperatures, some above 90°C, you can imagine that besides your HHO gas, a lot of water vapor (steam) AND also acetic acid vapors will escape such a HHO generator. Thus you are losing your electrolyte if you use Vinegar, not so with NaOH and KOH.

See the article "Kolbe Electrolysis" for a more in-depth look into this organic reaction named after Adolph Wilhelm Hermann Kolbe.

Acetic Acid gives Ethane gas + Carbon-dioxide gas. So you get an un-useful gas CO2 (it extinguishes flames, doesn't promote explosions) and Ethane gas which is a flammable gas that will behave as a fuel. Your electrolyte, by the electrolysis process in your HHO dry cell cooks and vanishes trough your engine, you'll be left with plain water, without electrolyte, resistance goes up, amps go down, HHO gas production goes down, and your possible gain in MPG is pretty fast back to zero.

Using Sodium Sulfate in your HHO Generator:

The electrolysis of an aqueous solution of sodium sulfate using inert electrodes does produce hydrogen at the cathode and oxygen at the anode, but a neutral solution of sodium sulfate remains unaltered by the electrolysis.

Cathode Reaction: 4 H2O + 4 e(-) ==> 2 H2 + 4 OH(-)

Anode Reaction: 2 H2O ==> O2 + 4 H(+) + 4 e(-)

The overall cell reaction is: 6 H2O ==> 2 H2 + O2 +4 H(+) +4 OH(-)

Sodium sulfate is much weaker than lye, so you would need much more electrolyte and it quickly turns your water into a brown/red substance. Though it does not damage the electrodes in your HHO generator, it really does not look good. So the bottom line is that after all my experimentation I simply decided to stick to KOH for best production of HHO gas from my HHO Dry Cell Generators. Yes it is a caustic material, but just like any object or substance that can be potentially dangerous in the wrong hands, you simply need to study up on the material you are using and be responsible and keep it out of the reach of your children. NaOH or KOH, when used as electrolyte to produce HHO gas, from any type of HHO Generator is clean and will never damage your electrodes.

I hope that this helps those who are experimenting with HHO fuel devices.