This paper presents results of a study of the degradation of commercially available GaAs and AlGaAs light emitting diodes subjected to neutron bombardment at a TRIGA reactor. Devices were characterized using current-voltage and light output measurements prior to and following a sequence of neutron irradiations and after high temperature annealing. A model is derived which can be used to determine the lifetime damage constant product, τo
K, if the light output measurements as a function of IMeV equivalent neutron fluence are made at a fixed operating current. For current levels smaller than approximately 1 ma, τo
K and operating current is logarithmic with τo
K decreasing as current increases. Annealing at temperature up to 275°C recovers some of the neutroninduced damage but does not affect the validity of the model.