A process for purifying a polyol (per)fluoropolyether derivative [polyol (P)] from a mixture of hydroxyl (per)fluoropolyether derivatives [mixture (M)]. Such polyol (P) comprising one or more hydroxyl (per)fluoropolyether derivatives [PFPE (OH)] comprising at least one (per)fluoropolyoxyalkylene chain (chain Rf) and at least one end-group having formula (t3) —CF2CH2OCH2CH(OH)CH2OCH2CH(OH)CH2OH. Such mixture (M) comprising the polyol (P) and at least one PFPE (OH) different from the polyol (P) and comprising at least one chain Rf and at least one end-group selected from end-groups having formula (t1) —CF2CH2OH and formula (t2) —CF2CH2OCH2CH(OH)CH2OH. The process comprises the steps of: 1) reacting the mixture (M) with a ketone, an aldehyde or a combination thereof to yield corresponding mixture of cyclic ketal/acetal (per)fluoropolyether derivatives [PFPEs (OH)p] [protected mixture (P)]; 2) carrying out a molecular distillation of the protected mixture (P) to isolate a protected product heavy residue [product (Pr)]; 3) hydrolyzing the product (Pr) to yield deprotected product [product (Pd)]; and 4) carrying out a distillation under reduced pressure of the product (Pd) to obtain polyol (P).