Dimethylchlorophosphine, PMe(2)Cl reacts with the hydroxyl groups on silica at room temperature to yield the chemisorbed speciwes SiOP=O(Me(2)), gaseous HCl, and gaseous dimethylphosphine, PMe(2)H. rue reaction does not yield SiOPMe(2) in detectable amounts. A mechanism of the reaction has been deduced, involving chlorination of the silica, and the generation of Me(2)P=O(H) as an intermediate species; this subsequently reacts with PMe(2)Cl to produce a second intermediate Me(2)P=O(Cl). The overall reaction is 2SiOH + 2PMe(2)Cl --> SiCl + HCl + Me(2)PH + SiOP=O(Me(2)).