Three-phase equilibrium conditions of (CH(4) + C(2)H(6) + C(3)H(8)) mixtures (V) + hydrate (H) + aqueous solutions of sodium dodecyl sulfate (L(w)) are determined using a sapphire cell apparatus according to an isochoric isothermal dissociation method at four temperatures, 275.2 K, 277.0 K, 278.8 K, and 2.80.6 K. The propane mole fraction in each equilibrium state is from 0.45 % to 16.98 %. Sodium dodecyl sulfate was used as a kinetic promoter as it has been shown that it has no influence on the phase equilibrium. The experimental data are in accord with those calculated by the hydrate thermodynamic models.