ABSTRACTIn this work, the mass transfer of aluminum ions in the electrocoagulation reactor was investigated using limiting current density technique by employing a novel rotating impeller anode. The effect of different anode rotational speeds of 75, 100, 150, 200, and 250 rpm with various anode diameters of 9.2, 10.2, and 11.2 cm on limited current values, mass transfer coefficient and COD removal efficiency were studied. Results showed the limited current values increase with the increase of the rotational speed and diameter of the impeller anode. Furthermore, the mass transfer coefficient increases with the increase of rotational speed and impeller diameter. Data for the conditions 11,852 < Re < 58,550 and 88 < Sc < 285 were found to fit the equation for the largest diameter of 11.2 cm; Sh = . Moreover, the maximum COD removal efficiency was at the largest anode diameter of 11.2 cm, validating the enhancement of aluminum mass transfer by increasing anode diameter.