The invention relates to preparation under sunlight illumination active, on substrate fixed thin films of ZnO-TiO2 based photocatalysts. The prepared photocatalysts provide for degradation of harmful organic components in water environment. The aim of the invention is improvement of reuse stability and photocatalytic activity under sunlight illumination of ZnO-TiO2 based photocatalysts. The aim of the invention is reached by addition of a definite amount of yttrium salt to zinc and titanium salts in spray pyrolytic process at 400 oC and calcination of the prepared thin film at 600–650 oC for 30–60 min. The additional calcination promotes crystallization of thin film and decreases structural defects.