A procedure is designed for the preparation of a photocatalytic bituminous road surface consisting of a stage involving the preparation of a bituminous base (2) with a thickness coming between 10 mm and 60 mm and containing gaps (5), and a subsequent stage for spreading a cement mortar (7) over said bituminous base (2), containing: a photocatalytic material for achieving a photocatalytic reaction, a plasticizing admixture suitable for fluidifying said mortar (7), and amorphous silicon dioxide suitable for making said mortar (7) more compact, said cement mortar (7) thus being suitable for coating the gaps (5) in said bituminous base (2).