A novel system for the determination of ammonia based on the chemiluminescent reaction between hypochlorite and luminol is presented. The technique of flow injection analysis was employed to automate the system. Ammonia reacts with hypochlorite to form monochloramine in basic solution which decreases the observed chemiluminescence intensity. Several interferents are identified, and the reasons why they interfere are discussed. The effects of interferents are Minimized through the use of a double-tube dialyzer where the ammonia is diffused across the dialyzer membrane into a recipient stream of hydrochloric acid.