Nanoparticles of alpha-Bi2Mo3O12 have been synthesized by a method that involves an amorphous complex precursor. The phase formation process, crystal structure and morphology of the synthesized samples were followed by TGA/DTA, XRD, TEM and SEM techniques. The effect of temperature of calcination on the surface area and optical properties of alpha-Bi2Mo3O12 nanoparticles has been also investigated. The photocatalytical activity of alpha-Bi2Mo3O12 nanoparticles was evaluated in the degradation of rhodamine B molecules in aqueous solution under visible light irradiation. The best photocatalyst was selected by evaluating the photocatalytic properties of samples with different calcination temperatures. The kinetic degradation of rhodamine B was adjusted with a first-order reaction with an apparent rate constant k' = 1.36 x 10(-2) min(-1) and t(1/2) = 51 min for the best material obtained. The mineralization degree of the dye to CO2 and H2O was around 56% after 100 h of irradiation. (C) 2008 Elsevier B.V. All rights reserved.