The title compound, C(13)H(15)NP(+)·Cl(-), was obtained by hydrolysis of the N-trimethysilyl derivative of methydiphenyl-imino-phosphine. The dihedral angle between the phenyl rings in the cation is 61.5 (3)°. In the crystal structure, inter-molecular N-H⋯Cl hydrogen bonds links the two components, forming a centrosymmetric 2 + 2 aggregate.