There was a spillage of oleum (fuming sulphuric acid H2S2O7) in a populated industrial area in Delhi on 4 December 1985. The visible plume from the spills caused some panic, and the event received considerable attention in the media. The feat of a possible similar event elsewhere has prompted the formulation of a mathematical model, with a view to estimating the ground level concentration of resulting H2SO4 mist. The main emphasis has been to stimulate the dispersion, with the inclusion of thermodynamic processes leading to a buoyancy dominated plume and scavenging process such as dry deposition of the acid-mist. Model results indicate that parts of the surrounding community and adjacent areas in the downwind direction are among the worst affected regions where the GLC is of the order of about 2.3 ppm. In general, model results are in good agreement with the reported extent of affliction. © 1990.