This document provides recommended guidelines for a comprehensive program to determine the useful life of chemical oxygen generators where useful life is defined as the sum of shelf and service life. Further, this document provides for a test program to determine with a sufficient level of confidence if the generators are suitable for further use and/or if the life limit has been reached. This program should include testing of generators of a representative sampling of a given year's production, of a particular part number, to provide a level of confidence sufficient to permit the units to be used for an additional specified time period.