The kinetics of a metastable, optically‐induced increase in the ESR in a‐Si:H have been examined between 77 and ∼500 K. Isothermal annealing (decay) and inducing (growth) curves indicate that the decay is bimolecular and thermally‐activated with an activation energy of ∼1 eV, and the growth is relatively temperature independent. At high incident light intensities the ESR increases monotonically roughly as a power law in time (Iαt β, β<1). At lower intensities β decreases with intensity.