Four-phase (SHhydrate + water-rich liquid + hydrocarbon-rich liquid + vapour) structure H (SH) hydrate equilibria of (methane + water + 2-methylbutane + magnesium chloride), (methane + water + 2,2-dimethylbutane + magnesium chloride), and (methane + water + methylcyclohexane + magnesium chloride) were measured in the temperature range from T = 271.55 K to T = 284.65 K, and the pressure range from p = 1.47 MPa to p = 9.75 MPa. The results for three ternary hydrates were found to be in good agreement with those in the literature. The addition of MgCl2exerted a substantial inhibition effect on hydrate formation. The hydrate equilibrium temperature and pressure were predicted by the Redlich–Kwong–Soave equation of state (RKS-EOS) using the Huron–Vidal second-order (MHV2) mixing rule incorporated with the modified UNIFAC model and Aasberg-Petersen et al.’s model. Good agreement was observed between the predicted conditions and experimental results. A small deviation was found as the system pressure increased.