Analytical methods for solid samples taken from a coal-fired power plant were developed and optimized in order to facilitate a comprehensive series of measurement campaigns aimed at trace metal balance determinations in various coal-fired power plants. Commercial reference materials with certified trace element contents were used as model samples. A procedure which had been previously developed for the analysis of fly ash was found to give good recoveries in the case of both coal fly ash and coal in a two-laboratory intercomparison. This procedure was based on microwave digestion in a mixture of HNO3 and HF in closed vessels. The digestion of samples of dolomitized limestone and gypsum rock was found to be successful under similar conditions but using a mixture of HNO3, HCl and HF, although the precision of the determination was not as good as in the case of coal and coal fly ash. The digestion procedures developed and tested in this work can be recommended as simple and uniform methods in the analysis of power plant samples for a number of trace elements, exclusive Hg.