The heat capacity data of the actinide(IV) oxides, fluorides and chlorides have been analysed. It is proposed that the data can be described as the sum of the lattice contribution and the contributions from f-electron excitation and a residual term, probably arising from interaction of d-electrons. It is demonstrated that the latter contribution becomes zero around T = (500 to 600) K. A similar approach for the entropies is given, from which the standard entropies of a number of An(IV) compounds have been estimated. (C) 2004 Elsevier Ltd. All rights reserved.