Abstract: A method for functionalizing a cellulose-based substrate by chemical deposition of at least one thin layer, from gaseous precursors. The method includes the provision of a substrate including at least one sheet having a first face and a second face, of surface roughness greater than or equal to 0.1 ?m. The first face has a part superposed to another part belonging to the first face or to the second face. A spacing between said parts is conserved at least locally, so as to enable a diffusion of the gaseous precursors. The method also includes the gaseous chemical deposition of at least one thin layer on the substrate such as provided by diffusion of the gaseous precursors, the gaseous precursors diffusing at least in each spacing.