Chemical degradation products created during the operation of an -beam pumped, repetitively pulsed XeF laser with closed flow cycle capability are reported. From an initial lasing mixture of Ar/Xe/NF3, the degraded gas was found to contain N2F2(N2F4), CO2, nitrogen oxides, CF4, and SiF4. Gaseous species were identified by their infrared and ultraviolet absorption spectra. Also present was a solid material tentatively thought to consist of fluorocarbons and aluminum fluorides. The observed gas chemistry suggests methods for improving laser performance by prevention of contaminant buildup.