Tetramethylammonium hydroxide (TMAH) is a quaternary ammonium compound with the chemical formula C₁₂H₃₁NO. It appears as a colorless liquid and is highly soluble in water. TMAH is commonly used in various applications, including as a developer in the semiconductor industry and as a reagent in organic synthesis. TMAH is known for its strong alkaline properties, making it effective in etching and cleaning processes. However, it is also toxic and can be hazardous if not handled properly. Safety precautions are essential when working with TMAH to prevent exposure and ensure safe usage.