The principal objective of the combustion experiments was to obtain information on the nitric oxide formation process in a continuous flow combustion system in which the flame is stabilized by recirculation. Specifically, the factors affecting nitric oxide production in the recirculation zone were to be identified and the importance of nitric oxide production in the recirculation zone to overall nitric oxide production in the combustor was to be determined. A simplified experimental configuration was used to permit detailed examination of the nitric oxide formation process in the combustion. The amount of nitric oxide produced in the recirculation zone is known to depend on four principal factors--the recirculation zone volume, the temperature and residence time of the gas in the zone, and the O-atom concentration in the zone. The data were used to correlate nitric oxide production in the recirculation zone with the important zone characteristics.