The Hydrogen Oxidation Soil Bioassay was single laboratory tested as a potential method for monitoring hazardous wastes and hazardous waste sites. The bioassay is based on the rate of hydrogen consumption by soil microorganisms. Oxidation of hydrogen to water is inhibited when various pollutants are present in the soil and the rate of this reaction can be used as an indication of potential hazard to the soil ecosystem. The single laboratory evaluation included ruggedness testing, a determination of method sensitivity and precision, and tests to determine the limits of reliable measurement. Aqueous solutions of mercuric chloride were used as sample material during the evaluation. Some preliminary tests were also conducted using both organic compounds and actual hazardous waste samples. The bioassay was found to be 'rugged' in the sense that modest procedural variations did not produce an altered test result. The complete Hydrogen Oxidation Soil Bioassay protocol, the results of chemical analyses conducted on actual samples that were used during the single laboratory test, and the preliminary bioassay responses to different types of sample material are included in the project report.