Anatase nanocrystallites showing high surface area (similar to 62 m(2)/g) and good photocatalytic property have been obtained by pyrolyzing at 600 degrees C for 4 h an ammonium titanyl double sulfate precursor (alpha-(NH4)(2)TiO(SO4)(2)) synthesized via a redox approach, that is, by oxidizing an aqueous solution of titanium trichloride (TiCl3) with ammonium peroxodisulfate ((NH4)(2)S2O8), followed by reacting with ammonium sulfate ((NH4)(2)SO4).