Phosphonamidates, O,O-di-tert-butyl 1-piperidinyl phosphonamidate (BP-1) and O-tert-butyl di-1-piperidinyl phosphonamidate (BP-2), were synthesized by the reaction of phosphorus oxychloride and piperidine in the presence of triethylamine, followed by the reaction with tert-butyl alcohol in the presence of sodium hydride. The polymerization of GPE was carried out at 110-190 degreesC for 12 h with BP-l and BP-2 as thermally latent initiators (3 mol %). The polymerization with O-tert-butyl P-phenyl 1-piperidinyl phosphonamidate (BP) previously reported was also examined for comparison. No polymerization of GPE took place below 110 degreesC, whereas it proceeded rapidly above the temperature. The activity order was BP-2 > BP > BP-1. Epikote 828 was cured with BP (5 mol %) at 190 degreesC to afford the solvent-insoluble gelled epoxy resin quantitatively. A mixture of GPE and phosphonamidate BP (3 mol %) did not react at 50 degreesC for 4 months.