The invention relates to a transparent substrate based on glass or one or more polymers, or a ceramic or glass substrate, or a substrate made of architectural material of the type comprising a wall render, a concrete slab or block, architectural concrete, roof tile, material of cementitious composition, terracotta, slate, stone, metal surface or a fibrous substrate, based on glass of the mineral insulation wool type, or glass reinforcement yarns. This substrate is distinguished in that it is provided, on at least part of its surface, with a coating whose mesoporous structure exhibits photocatalytic properties and comprises at least partially crystallized titanium oxide. Process for manufacturing this substrate, its application in glazing, as architectural material or as mineral insulation wool is also described.