The polymerization of glycidyl phenyl ether (GPE) was examined with O,O-di-t-butyl phenylphosphonate (BP) as an initiator in the presence of several Lewis acids, ammonium salts, and methyl cyanoacetate. BP served as an excellent thermally latent initiator in the polymerization of GPE in the presence of ZnCl2 and Zn(acac)(2). Epikote 828 was cured with BP (5 mol %) in the presence of ZnCl2, at 150 degreesC to afford the solvent-insoluble gelled epoxy resin quantitatively, which was thermally more stable than was the one cured without ZnCl2. No curing took place at room temperature for 7 months.