The products of a Hungarian experimental plantation for energy crops were investigated. Young shoots of poplar clones (Populus x euramericana and Populus x interamericana), black locust (Robinia pseudoacacia), willow (Salix alba), and an herbaceous plant (Miscanthus sinensis) revealed unexpectedly similar thermal behavior in inert and oxidative atmospheres, as well. An 8-fold difference in the level of grinding did not result in substantial differences in the thermal decomposition. The effect of oxygen in the ambient gas was studied at low sample masses (0.2-0.4 mg) that excluded the overheating due to the high reaction heat of the combustion process. The presence of oxygen affects the decomposition from ca. 220 degreesC. Nevertheless, the extrapolated onset temperature of the hemicellulose decomposition is practically the same at 0, 5, and 21 V/V% oxygen. A group of 12 experiments, representing two grinding levels, three plant genera and four different heating programs were evaluated simultaneously by the method of least squares employing the model of independent pseudocomponents. All evaluated experiments were well described by the same set of kinetic parameters; only the parameters describing the peak area of the partial processes differed. A technique was recommended for the appropriate handling of the nonrandom errors in the simultaneous evaluation of experiment series.