Anatase nano-titania (TiO2) powder was prepared by using a sol-gel process mediated in reverse microemulsion combined with a solvent thermal technique. The structures of the obtained TiO2 were characterized by TG-DSC, XRD, TEM. The photocatalytic decomposition of methylene blue (MB) on nano-TiO2 was studied by using an internal air lift circulating photocatalytic reactor. The results show that the anatase structure appears in the calcination temperature range of 400-510 degrees C, while the transformation of anatase into rutile takes place above 510 degrees C. The homogeneous microstructure of nano-TiO2 particles was obtained with a size of around 10-15 nm. In the photocatalytic performance, degradation process follows pseudo first order kinetics with different dosages of photocatalyst and initial MB concentrations and optimal TiO2 dosage is 0.1 g/L with neutral medium. (C) 2013 Elsevier Ltd. All rights reserved.