Preparation of 1,1,2,3,3,3,-hexafluoropropyl methyl ether(HFE-356mec), a prospective foam blowing agent replacing CFC-11, has been studied under a basic condition. Etherification of hexafluoropropylene(HFP) with CH₃OH occurred in a liquid phase having basic catalysts. Reaction temperatures lower than 30 ℃ produced high yields and high selectivities of the ether product. The effect of temperature indicated that the amount of HFP dissolved in methanol may play the major role to control the production rate of the HFE-356mec.