The structural and morphological properties of mesoporous anatase nanopowders, synthesized by sol-gel method, have been modified by varying the duration of calcination, in order to obtain more efficient photocatalyst than Degussa P25 in the degradation of relatively large pollutant molecules (>1 nm in size). According to X-ray diffraction analysis, the crystallite size was increased from 13 to 17.5 nm with the increase of calcination time from 1 to 7 h. The analysis of nitrogen sorption experimental data revealed that all samples were mesoporous, with a mean pore diameters in the range of similar to 5-9 nm. The corrugated pore structure model was employed to evaluate pore structure tortuosity. Nanopowder properties have been related to the photocatalytic activity, tested in the degradation of metoprolol tartrate salt, selective beta(1)-blocker used in a variety of cardiovascular diseases, with molecular size of 0.610 nm x 1.347 nm. The study has demonstrated that samples calcined for 4 and 5 h have displayed higher photocatalytic performance than Degussa P25, whereas the sample calcined for 3 h has shown comparable activity. (C) 2013 Published by Elsevier Ltd.