A traditional pressure recovery system is the major obstacle to mobile chemical oxygen-iodine laser (COIL) for its huge volume. A cryosorption vacuum pump was used as the pressure recovery system for different buffer gases. It made COIL become a flexible, quiet and pressure-tight.Experiments were carried out on a verti-COIL, which was designed for N 2 and energized by a square-pipe jet singlet oxygen generator (JSOG). The output power with CO 2 was 27.3% lower than that with N 2 , but the zeolite bed showed an adsorption capacity threefold higher for CO 2 than for N 2 in the continuous operation. The great volume efficiency interested researchers.Chemical oxygen-iodine laser, COIL, buffer gas, cryosorption vacuum pump, recovery syste