Two copolymers of N-acryloylpyrrolidine and N-vinylpyrrolidone with a different ratio of monomeric units and two homopolymers; poly-N-acryloylpyrrolidine and poly-N-vinylpyrrolidone, were synthesized to study the effect of the composition of macromolecular compounds (MMC) on their inhibiting power during formation of gas hydrates. The composition of the MMC was confirmed by H-1 and C-13 NMR spectroscopy and the ratio of monomeric units in the copolymers was determined with the H-1 NMR spectra. The inhibiting power of the synthesized MMC was determined during hydrate formation.