Differently substituted hydrazinophosphanes of the type (Me3Si)(2)N-N(SiMe3)-(PRR2)-R-1 (R-1 = Cl with R-2 = Me, C6F5 and R-1 = Me, R-2 = C6H5) have been studied in the reaction with Lewis acids such as ECl3 (E = Al, Gil). For (Me3Si)(2)N-N(SiMe3)-P(Cl) (Me) and (Me3Si)(2)N-N(SiMe3)-P(Me)(C6H5), only adduct formation was found while a chlorine/methyl exchange reaction was observed for (Me3Si)(2)N-N(SiMe3)-P(Cl)R (R = C6H5 and C6F5) leading to the formation of (Me2ClSi)(Me3Si)N-N(SiMe3)-P(Me)R, which crystallize as ECl3 adducts. The free hydrazinophosphanes can be obtained by removal of the Lewis acid with the help of a strong base such as 4-(dimethylamino)pyridine (DMAP).