The effect of kinetic cooling due to the absorption of 10.6‐&mgr; CO2laser radiation in the atmosphere has recently been predicted. In this letter, experimental evidence for this effect is presented. Transient‐density increases due to the kinetic cooling have been observed in CO2&sngbnd;N2mixtures following the propagation of an ∼ 1‐&mgr;sec 0.5‐J CO2laser pulse through the gas. The experiments were performed with varying concentrations of CO2and the observed cooling and subsequent heating effects are explained using the usual three‐level approximation for vibrational‐energy transfer in CO2&sngbnd;N2, together with known relaxation rates.