Characteristics of lasing in optically pumped, vacuum deposited organic semiconductor thin films of tris-(8-hydroxyquinoline) aluminum doped with DCM laser dye are studied as a function of DCM concentration and ambient temperature. In contrast to inorganic laser diodes, the lasing wavelength, output power, differential quantum efficiency, and threshold pump energy of organic lasers are found to be independent of temperature in the range from 0 to 140 °C. In addition, no degradation in laser performance was observed at temperatures approaching 160 °C. ©1997 American Institute of Physics.