Inhibition of formation of methane hydrate with cubic structure CS-I and methane-propane (95.66 CH4 + 4.34 C3H8 mole %) hydrate with cubic structure CS-II by isothermal method and method of cooling at the constant rate of 2A degrees C/h, using 0.5% of a kinetic inhibitor (KIH) + 20.8% of the thermodynamic inhibitor (TIH) monoethylene glycol (MEG) is studied. It is shown that the synergic effect of increase in inhibiting capacity of a polymeric kinetic inhibitor (KIH) in the presence of 20.8% of MEG (TIH) is observed in the case of both methane hydrate and methane-propane hydrate inhibition. The synergy manifests itself in the form of increase in supercooling degree by 2.5-3A degrees C that is attained in the KIH + TIH system before the initiation of hydrate formation as compared to a system that contains no TIH (MEG). The induction time is shown to depend on the degree of supercooling in the system while inhibiting CS-1 and CS-II hydrates with 0.5% KIH + 20.8% MEG. The obtained data indicate that KIH + MEG antihydrate reagents can be used to inhibit formation of technogenous gas hydrates at < 0C temperatures.