A numerical dissolved oxygen routing model (DORM) is developed to determine total stream community photosynthesis (P) and community respiration rates (R) through iterative routing of two-station diel DO measurements. The model differs from existing procedures for diel curve productivity analysis; it uses the complete stream DO transport equation, including longitudinal dispersion, dependence of respiratory rate on water temperature and dissolved oxygen and wind dependent oxygen transfer through the water surface. The model, DORM, is more accurate than the traditional graphical procedures of diel curve analysis and is simple to apply. DORM is also valuable in an analysis of the results' sensitivity to the numerous coefficient and parametric assumptions required in diel curve analysis. The model is not a predictive DO model, but is designed for the interpretation of DO measurements in a stream, channel or river.