The main goal of this Study is to investigate the effects of alternating current (AC) on dye removal from aqueous solutions by electrocoagulation (EC). An EC system with parallel-connected aluminium electrodes was operated in batch mode. Two different aqueous dye Solutions were used: one was obtained from Dianix Yellow CC (DY) and the other was obtained using Procion Yellow (PY). The experiments employing direct current (DC) were carried Out using a DC power supply. The AC experiments were conducted using rectangular wave, which is produced with an adjustable time relay connected to the Output of DC power Supply. This current is called alternating pulse Current (APC) in order to refer AC system in this Study. Total organic carbon (TOC) and dye removal efficiencies were measured to assess treatment efficiency. Operating cost was calculated for both power Supply systems and alternating pulse Current was found Superior to direct current for the treatment of reactive and disperse dyes used in this study. (C) 2009 Elsevier B.V. All rights reserved.