Abstract Bi 2MO 6 (M = W or Mo) have been successfully synthesized using the citrate complex method. The samples were characterized by X-ray diffraction, Brunauer–Emmet–Teller surface area and UV–vis spectroscopy. The solids crystallized in the orthorhombic Aurivillius-type structure and display optimum light absorption properties to be used as photocatalysts. The photoactivity power of the samples was investigated systematically using the rhodamine B degradation under different irradiation wavelengths. The behaviour of the solids and the photodegradation mechanism was studied as a function of the irradiation light (UV or visible) employed. Direct solar light was also employed as irradiation source showing that this type of structures could drive to a plausible strategy for developing finest photocatalyst to degrade wastewaters by using solar light.