A small hydrogen fluoride mixing laser has been developed which produces cw radiation with excellent short‐term amplitude stability (variation less than ±1.5%) and requires only 14 liter/sec pumping capacity. Using a grating and a semitransparent mirror mounted on a piezoelectric crystal for laser cavity optics, the laser has been made to operate on a single molecular transition and also on a single cavity mode. By varying the cavity length it was possible to tune the laser over about 300 MHz. The gain of the laser was established at about 30% by measurement of mode pulling and also by direct gain measurement.