A hydrophobic paper or cardboard that has self-assembled silicon-oxide nanoparticles with functional silane groups and fluorocarbonated compounds linked directly to cellulose fibers of at least one surfaces thereof, with a Cobb value of 8 to 25 g/m2 and water contact angles of 100° to 140°, which can be used for packing foodstuffs. The hydrophobic paper or cardboard may be printed, is recyclable and exhibits improved adhesion in areas requiring adhesive bonding of paper or cardboard.