Ab initio molecular orbital (MP2/6-311G(d,p) and CASPT2/ANO) and density functional theory (DFT/IGLO-III) calculations have been applied to determine some basic properties of phenylphosphinidene (C6HsP). Geometries, harmonic vibrational wavenumbers, singlet-triplet energy gaps, heats of formation and hyperfine splitting constants have been calculated. Phenylphosphinidene has a triplet 3A2 ground state lying 22 + 3 kcal/mol below the closed-shell singlet I A~ state and some calculated properties are: heat of formation at 0 K A/~f~0 = 68 + 5 kcal/mol, vertical ionization energy IEv = 10.6 4-0.3 eV, electron affinity EAa = 0.89 + 0.3 eV, proton affinity PA = 140 4-5 kcal/mol and isotropic hyperfine splitting constant a(3~P) = 66 4-3 G. The open-shell singlet ~A2 state is also a low-lying state having comparable energy with the ~A~. The properties of C6HsP are similar to those of methylphosphinidene (CH3P). The singlet-triplet gap (~A'-3A2) in CH3P amounts to 26 4-3 kcal/mol. Relative to the CH3P, the phenyl group has a small effect on the singlet state but seems to destabilize the triplet state and thereby reduce the singlet-triplet gap.