14The aim of the work was to prepare nanosized In2O3 and Ga2O3 photocatalysts for degradation of 15Perfluorooctanoic acid (PFOA) in water. Their commercial references along with TiO2 were used as 16 a comparison basis. The characterization of the materials proved that successful preparation of cubic 17In2O3 and monoclinic ß-Ga2O3 were achieved via solvothermal and hydrothermal methods, 18 respectively. The effect of different parameters such as catalyst dosage, UV light source and 19 utilization of inorganic oxidant in PFOA treatment were evaluated. In2O3, photocatalyst was the most 20 efficient in the degradation of 15 mgL -1 PFOA under UVB irradiation and synthetic air reaching 27% 21 of degradation, which was 20 percentage points higher than for commercial In2O3. This is proposed 22 to be partly due to significantly higher specific surface area of the self-made In2O3 and smaller 23 crystallite size and partly due to more efficient absorption of UVB light compared to the other tested 24 materials. Addition of KBrO3 did not improve the activity of self-made In2O3.