Abstract: Test and man-rating of an oxygen generation system required analytical methods for evaluating system performance both in the laboratory and on the aircraft. The Oxygen System Analyzer is capable of monitoring four performance variables which include: (1) system gas flow rate, (2) product oxygen concentration, (3) system outlet pressure, and (4) aircraft cabin pressure. The analyzer is a portable tester designed to be used on a frequent basis to ascertain system performance and assure reliability and safety. The device may be used either in preflight system checkout mode or to assess in-flight performance characteristics and compliance with design specifications. The analyzer is packaged in a flight worthy case (20.times.13.times.8.5 inches, 31 pounds) and operates from a 12 volt rechargeable power system for 8-10 hours. Data is handlogged from digital panel meters.