Waterborne epoxy resins were prepared by reacting epoxy resins with different molecular weights (360,900,1700,3200) with diethanolamine. The resins were then neutralized with 10% by wt acetic acid and emulsified in water. The resins were applied onto steel panels by a cathodic electrodeposition procedure. The deposition behaviour of the reins was studied using the effect of voltage-time (at constant current) and current density-time (at constant voltage) variations on the determined coulombic efficiency and the throwing power.