Despite the potential applications of γ-CuI thin films that involve significant temperature variations, few studies focus on the thermal stability of this material. We carried out post deposition annealing at different temperatures under argon and air atmospheres on γ-CuI thin films to stabilize and optimize the optoelectronic and thermoelectric performances. Electrical temperature measurements reveal an irreversible evolution during the first annealing treatment, with a systematic decrease of the conductivity irrespective of the atmosphere used. The annealing process under argon at 300 °C followed by air at 150 °C allowed stabilizing and optimizing the electrical conductivity at 152 S m−1...