Based on a pressure-modulated absorption technique, a novel nondispersive electrooptical gas analyzer has been designed, fabricated, and tested. Key features of this new gas analyzer technique include long-term zero and calibration stability. The technique was investigated for carbon dioxide (co2), carbon monoxide (co), methane (ch4), and nitrogen dioxide (NO2). The analyzer was capable of measuring the three species CO, co2, and NO2. It is a compact (300 cu in) package, is battery powered, and weighs 15 lb. Approximately 30 readings of each gas may be made on a single battery charge. Operating principles and performance data are included in the report.