Potassium methanesulfonate is an organic salt with the chemical formula CH3SO3K. It is a white crystalline powder that is highly soluble in water and polar organic solvents. Its structure features a simple methyl group attached to a sulfonate anion, paired with a potassium cation. This compound serves primarily as a versatile reagent in organic synthesis. It is commonly used as a mild base or a source of the methanesulfonate anion in various reactions. A significant and growing application is in the field of energy storage, where it is investigated as a component or additive in aqueous or organic electrolytes for batteries and supercapacitors, owing to its good ionic conductivity and electrochemical stability. Potassium methanesulfonate is also utilized in electroplating baths and as a catalyst or intermediate in specific chemical processes. It is generally considered to have low toxicity, but standard laboratory safety precautions for handling fine powders and chemicals should be observed.