Mixtures of magnesium chloride and MeOH were studied as mixed thermodynamic inhibitors of hydrate formation. The equilibrium P,T-conditions for methane hydrate decomposition in the presence of binary solutions H 2 O—MeOH and H 2 O—MgCl 2 and ternary solutions H 2 O—MeOH—MgCl 2 were determined using an isochoric method in a stirred autoclave. Measurements were made at pressures of 3.5-9.5 MPa; MeOH concentrations, 0-25 mass%. The salt content in the aqueous solutions was constant at 5 mass%. The results showed that mixed samples containing MeOH and MgCl 2 gave the largest thermodynamic shifts of hydrate formation as compared to samples with MeOH at the same inhibitor mass fraction. The larger thermodynamic shift was related to synergism between the affects of MgCl 2 and MeOH in the aqueous solution.