A cell head for an electrolytic cell includes a generally tubular protective insert concentrically positioned within the head to shield the inner side walls thereof from the scouring action of corrosive gas bubbles produced during electrolysis within the cell. The insert includes a lower connecting flange which fits between the mating connecting flanges of the cell head and its underlying electrolyte tank to block off access of gas bubbles rising through the electrolytic within the tank to the inner side walls of the cell head. The insert is readily replaceable without replacing the entire cell head.