N-Iodo-triphenylphosphaneimine, Ph3PNI, has been prepared by thermolysis of the donor acceptor complex [Me3SiNPPh3·ICl] in boiling acetonitrile in the presence of potassium fluoride. Both compounds have been characterized by IR spectroscopy and by crystal structure determinations. [Me3SiNPPh3 · ICl]: Space group P1̄, Z = 2, a = 888.3(1), b = 1070.7( 1), c = 1310.2( 1) pm, α = 95.15( 1)°, β = 108.67( 1)°, γ = 97.78( 1)° at 20°C. The complex has a molecular structure in which the N atom of the phosphaneimine is connected with the iodine atom of the ICI molecule in a linear arrangement N-I-Cl with bond lengths N-I = 232.7 pm, I-Cl = 255.37 pm. \Ph3PNI: Space group P21/n, Z = 4, a = 952.8(1), b = 1800.8(2), c = 1003.6(1) pm, β = 110.25(1)° at -50°C. The compound forms monomeric molecules with bond lengths PN = 159.1 pm, I-N = 205.6 pm and an INP bond angle of 113.3°.