Copolymers of 4-vinyl-1,2,3-triazole and 1-vinylimidazole (VI) were obtained by radical copolymerization of (4-vinyl-1H-1,2,3-triazol-1-yl)methyl pivalate with VI followed by alkali hydrolysis. Reactivity ratios of the triazole and imidazole monomers are 0.51 and 0.30, respectively. Theoretical quantum-chemical calculations by the PM3 semiempirical method give close values, which show that the obtained reactivity ratios reflect the activity of the vinyl groups. Polyelectrolyte properties of the copolymers were studied by potentiometric titration. Hydrogen bonds between the protonated triazole cycle and the triazole or imidazole units were found to considerably influence the solubility and solution properties of the copolymers. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012