Gaseous and particulate emissions from heavy-oil fueled power plants in Hungary were studied. Since fly ash is a heterogeneous mixture of different particle types, average compositions obtained by bulk analytical methods are not characteristic for the deposition and environmental impact studies of trace elements. Therefore single particles obtained from both the flue gas and the electrostatic precipitator were analyzed by a variety of micro-analytical methods. The usefulness of the single particle electron probe microanalysis (EPMA) is shown for characterizing the different particle types of oil fly ash. The application of the morphological and chemical parameters obtained by this method in the modeling of the vanadium deposition due to oil fly ash emission is demonstrated. Particles characteristic for oil combustion were observed in the aerosol sample collected in the vicinity of a heavy-oil fueled power plant using single-particle EPMA.