Poly(N-methyl-5-vinyltetrazole-co-5-vinyltetrazole) (P(MVT-VT)) with different N-methyl-5-vinyltetrazole (MVT) contents was synthesized via the method of click chemistry and the methylation thereafter. The chemical structure of the copolymers was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). Compared with that of poly(5-vinyltetrazole) (PVT), the solubility of P(MVT-VT) is improved. The chemical oxidation stability of the copolymer increases with increasing substitution value of the methyl group on the tetrazole ring. H3PO4 and imidazole (Imi) blended PVT and P(MVT-VT) composite membranes were prepared. The proton conductivity of P(MVT-VT)/H3PO4 and P(MVT-VT)/Imi composite membranes decreases with increasing MVT content. After the methylation of the tetrazole ring, the amphoteric properties of P(MVT-VT) is improved, which means either acid or base blended P(MVT-VT) can exhibit suitable proton conductivity. POLYM. ENG. SCI., 2012. (C) 2012 Society of Plastics Engineers