N-Chloro- or N-bromo-bistrifluoromethylamine undergoes a stepwise substitution reaction with (CF3)3M (M = P, As) to give [(CF3)2N]nP(CF3)3 –n(n= 1, 2, 3) and [(CF3)2N]nAs(CF3)3 –n(n= 1, 2). The corresponding reaction between (CF3)3Sb and (CF3)2NCl gave SbF3, CF3Cl, and CF3NCF2. The 19F n.m.r. spectra are recorded.