The three-phase equilibrium lines of the SF6 + H-2 mixed gas hydrate system were measured by the method of continuous measurement using a quartz crystal microbalance. The gas-hydrate equilibrium data were obtained at pressures ranging from (0.3 to 4.5) MPa and at temperatures from (279.15 to 283.15) K. The nuclear magnetic resonance (NMR) spectra of x(H2) = 0.75 mixed gas hydrate at pressures of (4.5 and 5.5) MPa and at a temperature of 279.65 K showed the presence of encaged hydrogen in small cages. The hydrogen content in the mixed feed gas varies from x(H2) = 0 to 0.90.