Radiation curable composition for preparing a hybrid sol-gel layer on a surface of a substrate, wherein said composition comprises: (i) At least one radiation curable (i.e. polymerizable and/or crosslinkable) material capable of being polymerized and/or crosslinked by a cationic polymerization reaction upon exposure to a radiation, said radiation curable material comprising at least two cationically polymerizable functional groups; preferably selected from among cyclic ether groups such as epoxy, and oxetanyl groups, and vinyl ether functional groups; preferably, said epoxy groups are part of a glycidyl or glycidyloxy group; (ii) A combination of at least one organofunctional silane of formula: R (4-m) - Si-(OR') m in which: - m is a number between 1 and 3, preferably m is 3; - OR' is an hydrolysable group; and - R is a hydrocarbyl group optionally containing at least one heteroatom, selected from among oxygen, sulphur, and nitrogen atoms; and of at least one other silane selected from among the group consisting of a poly(alkoxy siloxane) wherein the alkoxy group has from 1 to 20C, and a bissilane of formula R 1 [-Si(OR') 3] 2 in which: - OR' is an hydrolysable group, and - R 1 is a bivalent hydrocarbyl group optionally containing at least one heteroatom, selected from among oxygen, sulfur, and nitrogen atoms, and mixtures thereof;; and (iii) At least one cationic photoinitiator; preferably the cationic photoinitiator is combined with a sensitizer. (i) At least one radiation curable (i.e. polymerizable and/or crosslinkable) material capable of being polymerized and/or crosslinked by a cationic polymerization reaction upon exposure to a radiation, said radiation curable material comprising at least two cationically polymerizable functional groups; preferably selected from among cyclic ether groups such as epoxy, and oxetanyl groups, and vinyl ether functional groups; preferably, said epoxy groups are part of a glycidyl or glycidyloxy group; (ii) A combination of at least one organofunctional silane of formula: R (4-m) - Si-(OR') m in which: - m is a number between 1 and 3, preferably m is 3; - OR' is an hydrolysable group; and - R is a hydrocarbyl group optionally containing at least one heteroatom, selected from among oxygen, sulphur, and nitrogen atoms; and of at least one other silane selected from among the group consisting of a poly(alkoxy siloxane) wherein the alkoxy group has from 1 to 20C, and a bissilane of formula R 1 [-Si(OR') 3] 2 in which: - OR' is an hydrolysable group, and - R 1 is a bivalent hydrocarbyl group optionally containing at least one heteroatom, selected from among oxygen, sulfur, and nitrogen atoms, and mixtures thereof;; and - m is a number between 1 and 3, preferably m is 3; - OR' is an hydrolysable group; and - R is a hydrocarbyl group optionally containing at least one heteroatom, selected from among oxygen, sulphur, and nitrogen atoms; - OR' is an hydrolysable group, and - R 1 is a bivalent hydrocarbyl group optionally containing at least one heteroatom, selected from among oxygen, sulfur, and nitrogen atoms, and mixtures thereof;; and (iii) At least one cationic photoinitiator; preferably the cationic photoinitiator is combined with a sensitizer.