A membrane for an electrochemical device, said membrane comprising, preferably consisting of: (a) at least one fluoropolymer hybrid organic/inorganic composite comprising inorganic domains [polymer (F-h)], said hybrid being obtained by reaction between: - at least one fluoropolymer [polymer] that is a partially fluorinated fluoropolymer comprising recurring units derived from vinylidene fluoride, at least one monomer of formula: wherein each of R1, R2, R3, equal or different from each other, is independently a hydrogen atom or a C 1 -C 3 hydrocarbon group, and R OH is a C 1 -C 5 hydrocarbon moiety comprising at least one hydroxyl group, and - (iii) recurring units derived from at least one fluorinated monomer different from VDF wherein polymer has an intrinsic viscosity measured in dimethylformamide at 25 °C higher than 0.09 I/g and lower than 0.6 I/g; and - at least one metal compound [compound] of formula: X 4-m AY m wherein m is an integer from 1 to 4, A is a metal selected from the group consisting of Si, Ti and Zr, Y is a hydrolysable group, X is a hydrocarbon group, optionally comprising one or more functional groups, wherein the inorganic domains are obtained by grafting at least one compound to the polymer through reaction of said a least one compound with at least a fraction of the R OH groups of the (meth)acrylic monomer; and (b) a liquid medium [medium]. (a) at least one fluoropolymer hybrid organic/inorganic composite comprising inorganic domains [polymer (F-h)], said hybrid being obtained by reaction between: - at least one fluoropolymer [polymer] that is a partially fluorinated fluoropolymer comprising recurring units derived from vinylidene fluoride, at least one monomer of formula: wherein each of R1, R2, R3, equal or different from each other, is independently a hydrogen atom or a C 1 -C 3 hydrocarbon group, and R OH is a C 1 -C 5 hydrocarbon moiety comprising at least one hydroxyl group, and - (iii) recurring units derived from at least one fluorinated monomer different from VDF wherein polymer has an intrinsic viscosity measured in dimethylformamide at 25 °C higher than 0.09 I/g and lower than 0.6 I/g; and - at least one metal compound [compound] of formula: X 4-m AY m wherein m is an integer from 1 to 4, A is a metal selected from the group consisting of Si, Ti and Zr, Y is a hydrolysable group, X is a hydrocarbon group, optionally comprising one or more functional groups, wherein the inorganic domains are obtained by grafting at least one compound to the polymer through reaction of said a least one compound with at least a fraction of the R OH groups of the (meth)acrylic monomer; and - at least one fluoropolymer [polymer] that is a partially fluorinated fluoropolymer comprising recurring units derived from vinylidene fluoride, at least one monomer of formula: wherein each of R1, R2, R3, equal or different from each other, is independently a hydrogen atom or a C 1 -C 3 hydrocarbon group, and R OH is a C 1 -C 5 hydrocarbon moiety comprising at least one hydroxyl group, and - (iii) recurring units derived from at least one fluorinated monomer different from VDF wherein polymer has an intrinsic viscosity measured in dimethylformamide at 25 °C higher than 0.09 I/g and lower than 0.6 I/g; and - at least one metal compound [compound] of formula: X 4-m AY m wherein m is an integer from 1 to 4, A is a metal selected from the group consisting of Si, Ti and Zr, Y is a hydrolysable group, X is a hydrocarbon group, optionally comprising one or more functional groups, wherein the inorganic domains are obtained by grafting at least one compound to the polymer through reaction of said a least one compound with at least a fraction of the R OH groups of the (meth)acrylic monomer; and wherein m is an integer from 1 to 4, A is a metal selected from the group consisting of Si, Ti and Zr, Y is a hydrolysable group, X is a hydrocarbon group, optionally comprising one or more functional groups, wherein the inorganic domains are obtained by grafting at least one compound to the polymer through reaction of said a least one compound with at least a fraction of the R OH groups of the (meth)acrylic monomer; and (b) a liquid medium [medium].