The low-temperature heat capacity of synthetic huttonite ThSiO4 has been measured from T=(2 to 300) K. The sample was synthesised successfully from SiO2 and ThO2 by solid-state reaction at T= 1873 K at atmospheric pressure. From the calorimetric results, the value for the standard entropy S-m degrees (ThSiO4, huttonite, 298.15 K) = (104.3 +/-2.0) J . K-1 . mol(-1) has been obtained. This value indicates that the entropy of reaction from SiO2 and ThO2 is negative, giving a positive entropy term (-T . Delta S-r) of the Gibbs free energy of reaction. The implications of this finding are discussed extensively. (C) 2008 Elsevier Ltd. All rights reserved.