An experimental investigation was made of the characteristics of a photodissociation laser operating on the B–X (353 nm) and C–A (485 nm) transitions of the excimer XeF. The laser was pumped with vacuum ultraviolet radiation from an open high-current discharge. The energy in a laser pulse and the average specific output energy reached values of respectively 28 J and 18 J/liter at 353 nm and 14.5 J and 10 J/liter at 485nm. Measurements were made of the instantaneous lasing efficiency, defined as the ratio of the laser output power to the electrical input power from the pump source. At the maximum of a laser pulse the efficiency reached 0.8% at 353 nm and 1 % at 485 nm (corrected for the geometrical utilization factor of the pump source radiation). It was established that the pump source efficiency was 7.5–8.5% and that the quantum efficiency of the formation of XeF(B) averaged over the pump band was 85 ± 5%. Ways of raising the laser efficiency to ~ 2% were considered.