Three air pollutants, SO2, SPM and NO?, which are identified as major pollutants in urban cities, have been considered for a comparative study between predicted and observed concentrations of these pollutants at different receptor points over Delhi. A receptor-oriented Gaussian plume model (IITLT) and Climatological Dispersion Model (CDM) have been used to estimate the long term concentration of non-reactive pollutants due to emissions from area and point sources. Modified stability parameters are used for low wind speed and calm intervals. Monthly mean concentrations of these pollutants for the period of November, December and January 1987–1988 have been computed and the results obtained from the two models are found to be close to the observed values for this period. An error analysis of 54 pairs of observed and predicted concentrations show that performances of both the models are highly satisfactory, giving an RMSE of 1.61 for IITLT Model and 1.50 for CDM.