Future long-term space missions, such as a manned mission to Mars, will require regenerative life support systems which will enable crews more self-sufficiency and less dependence on resupply. Toward this effort, a series of tests called the Lunar-Mars Life Support Test Project have been conducted as part of the National Aeronautical and Space Administration (NASA's) advanced life support technology development program. The last test in this series was the Phase III test which was conducted September 19 - December 19, 1997 in the Life Support Systems Integration Facility at the Johnson Space Center. The overall objective of the Phase III test was to conduct a 90-day regenerative life support system test with four human test subjects demonstrating an integrated biological and physicochemical life support system to produce potable water, maintain a breathable atmosphere, and maintain a shirt sleeve environment.During the Phase III test, the air was revitalized using a combination of physicochemical systems and biological systems. The physicochemical systems consisted of a four-bed molecular sieve carbon dioxide removal subsystem, a carbon dioxide reduction subsystem, an oxygen generation subsystem, and a trace contaminant control subsystem. A solid amine water-save carbon dioxide removal subsystem was also evaluated during portions of the test. These systems provided approximately 75% of the air revitalization. The remainder of the air revitalization was provided by a crop of wheat being grown in a separate chamber called the Variable Pressure Growth Chamber. This paper will describe the physicochemical air revitalization system in detail, and present performance results from the 90-day test.