In this paper, structural and photocatalytic properties of TiO2 nanopowders doped with 1 at.% of cerium, cobalt, cooper and iron have been compared. Nanoparticles were synthesized by sol-gel technique and characterized by SEM, EDS and XRD methods. Moreover, their photocatalytic activity was determined based on decomposition of methyl orange. Results were compared with undoped powder. The structural investigations have revealed that all prepared nanopowders were nanocrystalline and had TiO2-anatase structure. The average size of crystallites was ca. 4 nm to 5 nm. The distribution of the dopant was homogenous in case of all manufactured powders. Moreover, for TiO2 doped with Co, Ce and Cu, aggregation effect was not as large as for TiO2:Fe. The results of photocatalytic decomposition showed that self-cleaning activity of all prepared nanopowders was higher as compared to undoped one. Due to the efficiency of these reactions (after 5 hours) nanopowders can be ordered as: TiO2:Co > TiO2:Ce > TiO2:Cu > TiO2:Fe > TiO2.