The invention relates to an anticorrosion treatment process in which applied to an oxidizable surface of a solid metal substrate is a liquid solution, referred to as treatment solution, comprising: at least one alkoxysilane, and at least one cerium (Ce) cation; in a liquid aqueous-alcoholic composition, said treatment solution being suitable for being able to form, at the surface of the solid metal substrate, a hybrid matrix by hydrolysis/condensation of each alkoxysilane(s) and of each cerium (Ce) cation; the treatment solution having a molar ratio (Si/Ce) of silicon element of the alkoxysilane(s) with respect to the cerium (Ce) cation(s) of between 50 and 500; characterized in that the cerium (Ce) cation(s) has(have) a concentration between 0.005 mol/L and 0.015 mol/L in the treatment solution.