Abstract-The batteries containing materials which are dangerous for health and safety of environment. In some type of battery, its application should be replaced when the power get lost. The waste of used battery should be well manage or even reused again for other useful purpose to reduce dangerous risk for heal and environment. The zinc-carbon battery is a type of battery that can be used only one time, consist of carbon rod as positive terminal, zinc case as negative terminal, and mixture of carbon powder, ammonium chloride, and MnO 2 as electrolyte. Hydrogen sulfide (H 2 S) is impurities found in the biogas and should be purified before further application as fuel for engine. Hydrogen Sulfide (H2S) is rising problem for the engine since will caused acidity to lubricant and corrosive to metal part of the engine. In this research the carbon powder of electrolyte part of the used zinc-carbon battery is reused as desulfurizer. Clay is added as a binder to make possible to create a pellet. It is found that the carbon powder from used zinc carbon battery is excellent as desulfurizer by adding clay as binder Index Terms-Battery, zinc-carbon, carbon paste, desulfurizer, biogas.