A process for the purification of a tetraol PFPE derivative [tetraol (T)] of formula (I): HO—CH2—CH(OH)—CH2—O—CH2—CF2—O—Rf—CF2—CH2O—CH2—CH(OH)—CH2OH, wherein Rf represents a fluoropolyoxyalkene chain (chain Rf), from a mixture (M) of hydroxyl (per)fluoropolyether derivatives, said mixture comprising said tetraol (T) and at least one hydroxyl (per)fluoropolyether [PFPE (OH)] comprising a chain Rf terminated with at least one end group of formula: —CF2CH2OH; —CF2CH2O—CH(OH)—CH2—O—CH2—CH(OH)—CH2OH; said process comprising: step 1: reacting the mixture (M) with ketones and/or aldehydes so as to selectively protect couples of hydroxyl groups on vicinal carbon atoms by forming corresponding cyclic ketal/acetal derivatives, so as to yield a protected mixture (P); step 2: reacting residual hydroxyl groups of the mixture (P) with suitable functionalizing agents enabling substantial volatility modification, so as to obtain a functionalized protected mixture (Pf); step 3: fractional distillation of the mixture (Pf) so as to isolate the cyclic acetal/ketal derivatives of tetraol (T); and step 4: hydrolyzing the acetal/ketal derivatives of tetraol (T) so as to recover pure tetraol (T).