Aluminum–air fuel cell electrocoagulation was evaluated for arsenate removal during power production. Effects of operational parameters (type and concentration of individual and mixed supporting electrolytes and initial pH) were investigated. 1mgL−1 arsenate in 1L of anolyte (with 10mM NaCl) was reduced to 1μgL−1 in 4h, power density produced was 112mW/m2. 8mM Na2SO4 mixed with 10mM NaCl created optimal conditions as mixed supporting electrolyte. Power density increased to 308mW/m2 and arsenate was reduced to 15μgL−1 after 24h. This indicates aluminum–air fuel cell electrocoagulation is useful treatment process.