A process for preparing perfluoropolyethers of formula T-O—(RF)z-T′  (I) wherein: T, T' are end groups, z=0 or 1; RF is a perfluoro(poly)oxyalkylene chain containing one or more fluorooxyalkylene repeating units selected from the group consisting of (CF2O), —(CF(CF3)O)—, —(CF2CF2O)—, —(CF2CF(CF3)O)—, —(CF(CF3)CF2O)—, —(CF2CF2CF2O)—, —(CF2CF2CF2CF2O)—, and —(CF2)j—CFZ—O— wherein j is an integer from 0 to 3, and Z is a fluorooxyalkylene chain comprising from 1 to 20 repeating units selected from the above reported fluorooxyalkylene units; comprising the reduction of peroxidic perfluoropolyethers comprising one or more of the above defined repeating units by using gaseous hydrogen in the presence of a catalyst comprising one or more metals of the VIII group supported on graphitic materials.