A hollow cathode electrode, particularly useful in fluorescent lamps, comprises an outer metal sleeve, an inner metal sleeve disposed within the outer sleeve and an emissive mix disposed on the inner sleeve. In one embodiment, the inner sleeve is a folded cylinder having a square cross section disposed within a circular cylinder. The object of the present invention is to prevent heat loss from the inner sleeve and to minimize sputtering. The electrode of the present invention may also include a third exterior sleeve surrounding but not contacting the interior sleeve or sleeves.