The performance of clofibric acid (CA) degradation in Milli-Qwater and wastewater treatment plant (WWTP) effluent by solar/TiO2 and solar/ZnO was investigated in summer and winter seasons. The effects of NO3- and HCO3- anions, humic acid (HA), and H2O2 on CA photocatalysis were evaluated. Significant difference in CA degradation in two seasons was observed. Both NO3- and HCO3- anions adversely affected CA degradation, particularly at high HCO3- concentration. CA degradation slightly increased with 0.5 mg L-1 HA in solar/TiO2 in summer, but was significantly inhibited in winter at 20 mg L-1 HA. However, the inhibitive effect of 20 mg L-1 HA on CA removal in solar/ZnO had no remarkable difference in two seasons. The degradation in solar/TiO2/H2O2 was similar to that in solar/TiO2, but was inhibited obviously in solar/ZnO/H2O2. When applying photocatalytic process into WWTP effluent, degradation rates were apparently lower compared to Milli-Qwater and temperature caused a great adverse effect on CA elimination.