The current work focuses on studying the behaviour of cadmium, chromium, lead, and zinc in the burning of fuel mixtures in a bubbling fluidised bed facility. The fuel mixtures of interest are sawdust or peat, blended with refuse-derived fuel pellets. The paper reports the results from full-scale measurements, chemical analyses of power plant streams, and theoretical predictions. Special interest is directed towards the vaporisation tendency of the elements within the bed region of the boiler, although the reactions in the freeboard of the installation are also studied. The results show that most of the trace elements escape the bed and are recaptured in the condensed ash streams of the unit. The theoretical method predicts cadmium to volatilise from the bed. Lead and zinc are likely to be captured in the bottom ash, but it appears that the theoretical approach taken in this paper tends to overpredict the volatility of these elements. Chromium is not volatilised to any greater extent, as compared with the other elements in the study.