Defect density as a function of light exposure time and the value of the saturation defect density in undoped hydrogenated amorphous silicon (a‐Si:H) have been measured. We varied conditions of temperature and light intensity to test the predictions of both a stretched exponential description of the kinetics and the steady‐state solution to the underlying rate equation. A stretched exponential fits the time dependence, with a stretching parameter that increases and a time constant that decreases with temperature over the range 270 to 360 K. The saturation density of light‐induced defects is both temperature and intensity dependent in the range 420–480 K for generation rates 6×1020to 2×1022cm−3sec−1. The observed decrease in saturation density with increasing temperature and increase in saturation density with increasing intensity are consistent with the model predictions.