The invention relates to 1,2,2,2-tetrafluoroethyl-fluoromethyl ether, to a process for preparing it and to its use as inhalation anesthetic. The present invention relates to the 1,2,2,2-tetrafluoroethyl-fluoromethyl ether of the formula and to a process for preparing it, which comprises subjecting a 1,2,2,2-tetrahalogenoethyl-methyl ether of the formula in which n is 0 to 3 and m is 0 or 1, to a partial photochlorination under formation of the 1,2,2,2-tetrahalogenoethyl-chloromethyl ether of the...