A simple one-pot preparation of (2,4,6-Trimethylbenzoyl)diphenylphosphine oxide (TPO) by employing the low-cost triphenylphosphine oxide (Ph₃PO) as the starting material was described. Reaction with trimethylsilyl chloride (TMSCl) that transforms the intermediate sodium diphenylphosphonite (Ph₂PONa) into (trimethylsilyl)oxy)diphenylphosphine (Ph₂POTMS) is the key for the high yield of TPO. The reactions of Ph₂PONa with other silyl chlorides are discussed.