Dimethylchlorosilane is prepared by reacting 1,2-tetramethyldichlorodisilane with hydrogen chloride in the presence of a catalyst mixture of a) palladium, b) a tertiary amine, and c) a tertiary phosphine having at least one phenyl group having at least one functional group other than hydrogen. The catalyst does not lose its activity upon contact with hydrogen chloride at low temperatures and ensures production of dimethylchlorosilane in high yields.