We report electroluminescence degradation studies on tris(8-hydroxyquinoline) aluminum(Alq3)-based organic light emitting devices (OLEDs) with Mg:Ag cathodes in ambient conditions. The nonemissive spots in the OLEDs are studied via optical and fluorescence microscopy and via microscopic infrared spectroscopy. Studies reveal that a majority of the nonemissive spots are caused by the growth ofMg(OH)2sites at theAlq3/Mg:Aginterface, associated with local degradation of theAlq3layer. In addition, the growth of elevated cathode bubbles, which also lead to nonemissive spots, is found to be caused by gas evolution from the galvanic corrosion of the Mg/Ag couple as well as from the electrolysis of absorbed moisture. ©1998 American Institute of Physics.