The molecular structure of 5-[(triphenylphosphoranylidene)hydrazono]- exo-3-azatricyclo[5.2.1.0]decane-4-one is determined. The CHNOP compound crystallizes in the space group P−1: a = 9.2163(9) Å, b = 11.1102(11) Å, c = 11.9397(12) Å, α = 74.284(2)°, β = 78.532(2)°, γ = 72.004(2)°.