A repository of 38 gaseous organic compounds in compressed gas cylinders has been established by the U.S. Environmental Protection Agency. This repository was established to provide standards for source test performance audits, that is, quantitative quality assurance tests. Among these compounds are ten halogenated organic species, which are the focus of this study. These compounds are: chloroform, 1,2-dichloroethlene, trichloroethylene, 1,1-dichloroethylene, perchloroethylene, vinyl chloride, methylene chloride, carbon tetrachloride, freon 113, and 1,1,1-trichloroethane. Stability studies of all ten compounds have been performed to determine the feasibility of using them as performance audit standards. Results indicate that all of the halocarbons tested are adequately stable to be used as reliable audit standards. Also included are source test performance audit results using these halocarbons.