Clofibric acid (CA) is a ubiquitous pollutant that is resistant to traditional wastewater treatments. Here, photoelectrocatalytic (PEC) degradation of CA using a FeOOH/P:BiVO4/rGO photoanode is investigated. The characteristics by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) on the electrode-electrolyte interface were performed to optimize different electrolyte conditions (Na2SO4 concentration, CA concentration, and pH). EIS is found to be a simple, fast method to study the electrolyte conditions for PEC decomposition of CA on BiVO4 composites electrodes. The experimental results demonstrated that the electrolyte conditions had an effect on the surface coverage of V5+/V4+ redox species and surface states related to ion/molecule distribution on the electrode surface. The optimum deposition time was 6 min. And the optimum electrolyte conditions were as follows: the concentration of Na2SO4 was 0.2 mol L-1, the concentration of clofibric acid was 5 mg L-1, and pH was 7. Under these conditions, FeOOH/P:BiVO4/rGO photoanode showed a removal rate of CA 96% in 6 h under visible light irradiation (lambda >= 420 nm). It also showed a good photoelectric stability. FeOOH/P:BiVO4/rGO photoanode showed a potential application in the photoelectrochemical degradation of CA. (C) 2019 Elsevier Ltd. All rights reserved.