A process for preparing (per)fluorohalogenethers having general formula (I): (R)nC(F)mOCAF—CA′F2  (I) wherein: A and A′, equal to or different the one from the other, are Cl or Br or one is selected from A and A′ and hydrogen and the other is halogen selected from Cl, Br; R═F, or a fluorinated, preferably perfluorinated, substituent, selected from the following groups: linear or branched C1-C20 alkyl more preferably C1-C10; C3-C7 cycloalkyl; aromatic, C6-C10 arylalkyl, alkylaryl; C5-C10 heterocyclic or alkylheterocyclic; when R is fluorinated or perfluorinated alkyl, cycloalkyl, arylalkyl, alkylaryl, it can optionally contain in the chain one or more oxygen atoms; when R is fluorinated it can optionally contain one or more H atoms and/or one or more halogen atoms different from F: n is an integer and is 1 or 2; m=3-n; by reaction of carbonyl compounds having formula (II): (R)pC(F)q(O)  (II) wherein: p is an integer and is 1 or 2; q is an integer and is zero or 1, R is as above; in liquid phase with elemental fluorine and with olefinic compounds having formula (III): CAF═CA′F  (III) wherein A and A′ are as above, at temperatures in the range from −120° C. to −20° C.