The utilisation of refuse-derived fuel (RDF) in energy production is restricted by their inorganic impurities, such as heavy metals and chlorine. In this contribution, three different types of RDF were studied by SEM-EDS. These materials originated from three locations: construction sites, households, and supermarkets. Several fuel samples of every type of RDF were used in this study. The compositional distributions of the inorganic particles were determined directly from each fuel and the results are presented as quasiternary diagrams. The presentation method makes it possible to identify inorganic particles such as sand, alkali metal chlorides, calcium chloride, gypsum, lime, titanium pigment, iron as an element or oxide, and metallic aluminium from fuel. The results can be used to discuss the origin of different inorganic components in these materials and serve as a base for discussion of the suitability to use each waste material as fuel. It also facilitates the design of appropriate purification steps that are needed. (c) 2006 Elsevier Ltd. All rights reserved.