Methyltriphenylphosphonium bromide is the organophosphorus compound with the formula [(C6H5)3PCH3]Br.

It is the bromide salt of a phosphonium cation.

It is a white salt that is soluble in polar organic solvents.

Methyltriphenylphosphonium bromide is produced by treating triphenylphosphine with methyl bromide:[1] Methyltriphenylphosphonium bromide is the principal precursor to methylenetriphenylphosphorane, a useful methylenating reagent.

This conversion is achieved by treating methyltriphenylphosphonium bromide with strong base.