The novel functionality of aromatic tetrazole derivatives with high nitrogen content predetermines a great interest to tetrazole-containing polymers. Poly(5-vinyltetrazole) is one of the most attractive polymers containing tetrazoles. The 4-chloromethyl styrene (CMS) was copolymerized with acrylonitrile (in various mole ratios) by free radical polymerization method at 70°C using α,α-azobis(isobutyronitrile) as an initiator. The reaction azide ion with copolymers, simultaneously with replacement of all the chlorine atoms in CMS units, causes the nitrile groups are entirely converted to tetrazole in dimethylformamide at elevated temperatures. The polymers, obtained in quantitative yields, were characterized by FT-IR and 1H NMR spectroscopy, differential scanning calorimetry, and gel permeation chromatograph studies. Thermal properties nitrogen-rich polymers show that explosive thermal degradation takes place at around 260°C. © 2013 Taylor & Francis.