Application of thermal dissociation of O2, developed within arc‐heated gas mixtures, followed by a sufficiently rapid convection to preserve O atom concentrations and subsequent CS2injection, has generated efficiently a CO laser medium. In preliminary experiments, this pumping technique has produced a 34‐W cw laser emitting over a band of vibration‐rotation transitions from 4.9 to 5.7 &mgr; from a 5‐cm active transverse optical cavity.