Hydrate formation conditions Of (CH4 + C2H4) and (CH4 + C3H6) binary gas mixtures in the presence of pure water were measured in a sapphire cell using the "pressure search" method. The experimental temperature-range was 273.7-287.2 K, and pressure-range was 0.53-6.6 MPa. Ethylene content in the gas mixtures varied from 7.13 to 100 mol%, and the propylene content varied from 0.66 to 71.96 mol%. The Chen-Guo hydrate model has been successfully applied to represent the measured data.