Equilibrium conditions of clathrate hydrates formed from propane and aqueous solutions of propanone and sodium chloride were experimentally measured at a temperature range of (264.7 to 276.9) K and pressures up to 0.514 MPa using an isochoric method. The equilibrium temperatures of the clathrate hydrates decrease as the propanone concentrations increase, indicating that propanone has an inhibiting effect on propane hydrate formation.