We present a hydrothermal method for synthesis of zirconia nanopowders: pure and with incorporated Si4+ ions. Zirconyl chloride and tetraethyl orthosilicate were used as precursors. As prepared powders were annealed at 600 degrees C and characterized using structural (XRD), morphological (SEM and TEM) and optical techniques (UV/vis DR, FTIR and photoluminescence spectroscopy). Their textural properties (BET method) and photocatalytic activity toward degradation of model compounds (tricholophenol and Rhodamine B) using simmulated solar light were obtained. We showed that by using hydrothermal synthesis method pure monoclinic ZrO2 highly crystalline powder can be obtained. Incorporation of Si4+ ions induced stabilization of tetragonal crystalline phase at room temperature and decreasing of particle sizes. Incorporation of Si4+ ions in zirconia matrix also resulted in increase of specific area of nanopowders. FTIR measurements were used as proof for existence of Zr-O-Si bond. Effective band gap of zirconia powders was reduced from 5 (pure ZrO2) to 3.8 eV for samples with Si4+ ions. All zirconia powders showed significant photocatalytic activity regarding degradation of triclorophenol and no activity regarding RB (Rhodamine B dye). Photocatalytic activity of zirconia was increased by incorporation of Si ions in the host matrix. The source of this observation is discussed correlating all obtained properties of pure and Si-incorporated nanopowders. Optimization of synthesis parameters and composition of zirconia samples obviously can lead to their photocatalytic activity comparable to Degussa TiO2 powder, famous and commercial photocatalyst. (C) 2016 Elsevier B.V. All rights reserved.