Recently, the semiconductor-mediated photocatalytic degradation of dyes has gained more and more attention. In the first chapter of the thesis, hierarchically porous TiO2 and macroporous TiO2 were successfully synthesized with a templating method. Structural and morphological differences between synthesized TiO2 and commercial TiO2 were found. Photocatalytic performance for the degradation of rhodamine B was studied. The specific surface area and porosity were found to be important for photocatalytic performance. Commercial TiO2 with the highest specific surface area and porosity showed better performance. In the second chapter, novel visible light responsive photocatalysts based on hierarchically porous NiTiO3/TiO2/NiO composites were synthesized. The chelating agent concentration, template content, and calcination temperature were varied to tune the specific surface area and porosity. The composition, structure, morphology, and photocatalytic activity of the composites and TiO2 synthesized using a similar approach were thoroughly characterized and their performance was compared. The TiO2 system showed better photocatalytic performance than the NT composites.