NOVELTY - Obtaining a platinum-doped titanium dioxide photocatalyst involves: (a) dissolving a titanium precursor in an organic solvent; (b) dissolving citric acid in an alcohol; (c) adding the solution obtained in step (a) on the solution obtained in step (b); (d) aging the solution; (e) drying the particles; (f) grind the particles; (g) sifting the particles; (h) calcining the product; (i) adding the product in solution of platinum in isopropanol; (j) agitating; (k) illuminating the product; (l) filtering on a filter plate particles; (m) washing with distilled water; and (n) drying in oven.    USE - The method is useful for obtaining platinum-doped titanium dioxide photocatalyst. The photocatalyst, in the presence of visible light, is useful for producing hydrogen from photocatalytic decomposition of liquid water (all claimed). It can also be used for photocatalysis and for power generation and storage.    ADVANTAGE - The main use of the materials is for the production of hydrogen, which can be used for generating inexpensive, sustainable power by so-called fuel cells.    DETAILED DESCRIPTION - Obtaining a platinum-doped titanium dioxide photocatalyst involves: (a) dissolving a titanium precursor in an organic solvent; (b) dissolving citric acid in an alcohol; (c) adding the solution obtained in step (a) on the solution obtained in step (b) and stirring; (d) aging the solution from step (c); (e) drying the particles obtained in step (d); (f) grind the particles obtained in step (e); (g) sifting the particles obtained in step (f); (h) calcining the product obtained in step (g); (i) adding the product of step (h) in solution of platinum in isopropanol, where platinum is in the range of 0.05-0.5 wt.% of platinum, and comes of a concentrated solution of hexachloroplatinic acid; (j) agitating; (k) illuminating the product obtained after step (j) for a time comprised between 4 and 8 hours using a lamp with a power of between 200 watts (W) and 600 W; (l) filtering on a filter plate particles obtained in step (k); (m) washing with distilled water, in the same crucible, the particles obtained in step (l) to analyze leachate and washing with water to verify the elimination of isopropanol of the particles obtained in step (l); and (n) drying in oven at a temperature between 100 and 140 degrees C of the particles obtained in step (m) deposited on a rectangular plate from porcelain so that it is spread evenly across its surface. An INDEPENDENT CLAIM is included for a platinum-doped titanium dioxide photocatalyst obtained from the method.