The three-phase, hydrate-water-rich liquid-vapor (HLV), equilibria of the binary guest mixtures containing CO 2 and N 2 were determined at the temperature range of 272-275K and different compositions of vapor phase. In addition, two phase equilibria of hydrate and vapor were also measured at three isothermal conditions of 274, 277 and 278K. The resulting P-x diagram indicates that CO 2 can be more contained than N 2 in the hydrate phase. More than 96mol% CO 2 in the mixed hydrate phase was obtained from a gas mixture of 17mol% CO 2 and 83mol% of N 2 at 274K. The addition of tetrahydrofuran (THF) as a hydrate promoter extended hydrate stability region by elevating equilibrium dissociation temperature and lowering pressure. The overall hydrate equilibrium results were found to agree well with the calculated ones.