H2and HBr are compared as cavity fuels in a 1‐kW arc‐driven cw HF chemical laser. Closed‐cavity power is presented as a function of fuel flowrate and lasing‐axis position. Peak power observed was ∼350 W with HBr, ∼600 W with HBr and He, and ∼1100 W with H2. Spectral content of the laser beam indicated dominant 1–0 and 2–1 vibrational transitions with H2, and 2–1 and 3–2 transitions with HBr.