The present invention provides a process for producing 1,1,1,3,3,3-hexafluoro-2-methoxypropane, wherein a novel compound, 2-methoxy-2-trifluoromethyl-3,3,3-trifluoropropionic acid or a salt thereof is decarboxylated, or wherein an olefin compound represented by chemical formula (4): CF2═C(CF3)(OCH3) is reacted with a fluorinating agent; and a process for producing 2-methoxy-2-trifluoromethyl-3,3,3-trifluoropropionic acid or a salt thereof by reacting a hydroxycarboxylic ester with a methylating agent and then hydrolyzing the reaction product, or hydrolyzing the hydroxycarboxylic ester and then reacting the resulting product with a methylating agent.In accordance with the invention, 1,1,1,3,3,3-hexafluoro-2-methoxypropane, which is useful as a raw material for, for example, the anesthetic Sevoflurane, can be produced efficiently and at low cost.