A performance study of oxygen self-rescuers from the United States and other countries was undertaken as an assessment of present worldwide technology. The apparatus were tested on a breathing and metabolic simulator in the life support laboratories of the Bureau of Mines. Parameters monitored during the testing were inhaled levels of co2 and o2, inhaled gas temperature, and breathing resistance. The metabolic demand placed on the apparatus represented the average demand of the 50th percentile miner performing a 60-min man-test 4, as described in 30 cfr 11h. Results presented include apparatus service life and subjective comments as well as averages and peaks of monitored parameters.