Aminolysis of the chlorinated poly(thionylphosphazene) [NSOCl(NPCl2)(2)](n) (2a) with several secondary amines NHR2 (diethylamine, piperidine, and pyrrolidine) yielded various hydrolytically stable poly[(amino)thionylphosphazenes] [NSO(NR2){NP(NR2)(2)}(2)](n) 6 (a, NR2 = piperidine; b, NR2 = pyrrolidine) in which chlorine atoms at both the phosphorus center and sulfur were replaced. In addition, treatment of 2a with different equivalents of several secondary amines (diethylamine, piperidine, and pyrrolidine), followed by addition of excess of n-butylamine, lead to a series of mixed-substituent poly[(amino)thionylphosphazenes] [NSO(NHR'){NP(NR2)(2)}(2)](n) 7 (NHR' = n-butylamine; a-c, NR2 = diethylamine; d, e, NR2 = piperidine; f, NR2 = pyrrolidine). The new moisture stable polymers were characterized by P-31, C-13, and H-1 NMR spectroscopy and elemental analysis. The molecular weights of the polymers 6a, 6b and 7a-7f were in the range of (M) over bar (w) = 3.4 x 10(4) - 1.1 x 10(5) and (M) over bar (n) = 3.1 x 10(3) - 5.0 x 10(4) according to GPC analysis in THF versus polystyrene standards. The thermal transition behavior was investigated by means of DSC. Glass transition temperatures (T-g's) of the poly[(amino)thionylphosphazenes] 6a,6b and 7a-7f depend on the content of secondary amine versus primary amine and were in the range of -13 to +27 degreesC. No melt transitions were detected.