A quantitative analysis of an HF cw chemical laser is presented that includes the influence of stimulated emission on the reacting medium. The numerically determined solutions encompass one-dimensional fluid mechanics, chemical kinetics, radiative de-excitation, and their mutual interaction. A comprehensive parametric study examines the effects due to changed plenum conditions, mixture ratios and cavity parameters. Best efficiency is obtained when the pumping is by the F + H 2 reaction. Pumping by the chain reaction sequence F + H 2 → HF(υ ≤ 3) + H and H + F 2 → HF(υ ≤ 6) + F results in substantially lower efficiencies due to increased HF-HF vibration-translation deactivation. Detailed discussions are presented of (1) vibration-vibration and vibration-translation energy exchange, (2) chemical efficiency, (3) mechanisms that cause lasing termination, and (4) cavity operation with a selective grating.