Concentrations of nitrogen-, oxygen- and sulphur-containing organic species observed by Kirton et al. [P.J. Kirton, J. Ellis, P.T. Crisp, The analysis of organic matter in coke oven emissions, Fuel 70 (1991) 1383-1389] in coke oven emissions have been compared with local equilibria for each heteroatom-containing set of species at coke oven temperatures. The equilibrium pressures of these species, together with values for some additional aromatic nitrogen and sulphur species in representative coke oven gases have also been calculated. It is found that nitrogen-containing species in the analysis by Kirton et al. are far from locally equilibrated, but the pressures of most nitrogenous species attain equilibrium levels within the range of typical coke oven temperatures. Oxygen-containing species are nearer to local equilibrium but absolute pressures observed in the full coke oven gases are in the majority of cases considerably higher than the predicted equilibrium levers. Too few sulphur-containing species were observed by Kirton et al. to draw conclusions based on local equilibrium comparisons, but the relationship between observed and predicted pressures in the full coke oven gas is consistent with fluid equilibration of sulphur compounds at elevated temperatures. The pressures of all nitrogen and sulphur-containing aromatic species are found to vary approximately linearly with the amount of nitrogen or sulphur in the coke oven gas. The equilibrium pressures of oxygen-containing species do not all vary linearly, and a fall in the oxygen concentration can lead to a large increase in the concentration of some species as a result of the effect of the water gas shift reaction on the available C:H ratio.