This work shows results of electrocoagulation of solutions containing arsenic. The continuous flow treatment consisted of an electrocoagulation reactor with two parallel iron plates and a sedimentation basin. The results showed that the electrocoagulation process of a 100 mg/L As(V) solution could decrease the arsenic concentration to less than 2 mg/L in the effluent with a current density of 1.2 A/dm2 and a residence time of around 9 min. Liquid flow was 3 L/h, and the DC current was reversed each 2 min. Increasing the current density from 0.8 to 1.2 A/dm2, the Fe3+ and OH- dosages increase too, and thereby favouring the As removal. On the other hand, it seems that increasing the current density beyond a maximum value, the electrocoagulation process would not improve further. This could probably be explained by passivation of the anode. © 2005 Elsevier Ltd. All rights reserved.