Experimental study of a supersonic pulsed, H2+F2 pumped HF laser is presented. The reactants are premixed and then expanded through a supersonic nozzle into the laser cavity, whereupon the reaction is initiated by an electrical discharge at a high repetition rate. The small‐signal gain of some of the laser lines was measured as a function of the distance downstream from the initiation point and as a function of the reactants concentration. The spectral content of a laser pulse was analyzed and the induction times between the initiation and the onset of lasing on different laser lines were measured. The output power was measured as a function of the discharge voltage, the discharge pulse frequency and the reactants concentration. The results are compared with the lasing characteristics of a cold reaction, H2+SF6 ‐pumped laser.