A thermophysical and thermochemical calorimetric investigation of UO2MoO4 was undertaken. The UO2MoO4 was synthesized by solid-state reaction of MoO3 and UO3 and characterized by X-ray powder diffraction and X-ray fluorescence methods. The temperature of fusion, T-fus = (1212 +/- 2) K, and the enthalpy of fusion, Delta H-fus degrees (1212 K, UO2MoO4, Cr.) = (16 +/- 1) kJ . mol(-1), were determined using DTA methods. The low-temperature heat capacity, C-p degrees(T), behaviour of UO2MoO4 was measured using adiabatic calorimetry from T = (6 to 301) K and the third-law entropy determined. S degrees = (192.8 +/- 0.8) J . mol(-1) . K-1 at T = 298.15 K is obtained. The enthalpy of formation of UO2MoO4 was determined using HE-solution calorimetry giving Delta H-f degrees(298 K, UO2MoO4, Cr.) = -(1985 +/- 8) kJ . mol(-1). From these data, the Gibbs energy of formation Delta(f)G degrees(298 K, UO2MoO4, cr.) = -(1836 +/- 8) kJ . mol(-1) is calculated. Smoothed C-p degrees(T) values between T = (0 and 300) K are presented along with values for S degrees and the functions [H degrees(T) - H degrees(0)] and [G degrees(T) - H degrees(0)]. (c) 2010 Elsevier Ltd. All rights reserved.