A repository of 45 gaseous compounds including hydrocarbons, halocarbon, and sulfur species has been established under contract with the U.S. Environmental Protection Agency (USEPA). The main objectives of the on-going project are (1) to provide gas mixtures to EPA, state/local agencies, or their contractors, as performance audits to assess the accuracy of source emission measurements in certain organic chemical manufacturing industries, (2) to examine the vendor's certified analysis of the gas mixtures by in-house analysis, (3) to determine the stability of the gas mixtures with time by in-house analysis, and (4) to develop new audit materials as needed. Thus far, 31 compounds have been used to conduct 214 different audits. The results of these audits and a description of the experimental procedures used for analyses and available stability data are presented in the status report. Generally the audit results are within 15 percent of the expected values.