Abstract: The main objective of this study is to investigate the removal of Ni(II) ions from water by electrocoagulation method under the effect of alternating current. AC is used in the electrocoagulation process in order to reduce the disadvantages of DC and to facilitate the effective current transfer between the anode and cathode. This process involves applying an alternating electric current to sacrificial aluminum electrodes inside a reactor tank. The coagulating Al ions generated from the electrodes react with Ni(II) ions in water forming flocs which precipitate. Several factors affecting efficiency of electrocoagulation are investigated. They include initial Ni(II) ion concentration, applied current density and inter-electrode distance. The power consumption for electrocoagulation increased proportionally when the current density, electrode gap and concentration of electrolyte in the solution were increased. The metal ions removal efficiency was reported to be between 86.80 and 99.50%.