Hydrate formation conditions of (CH4 + CO2 + H2S) ternary sour natural gas mixtures in the presence of pure water were measured. The experimental temperature range was (274.2 to 299.7) K, and the pressure range was (0.58 to 8.68) MPa. The hydrogen sulfide and carbon dioxide contents in the gas mixtures varied from (4.9 to 26.6) mol % and from (6.8 to 10.8) mol %, respectively.