The heat capacities of FePO4 and Fe-3(P2O7)(2) have been measured using a Quantum Design Physical Property Measurement System (PPMS) over the temperature range from (2 to 300) K. The phase transit ion due to the Fe3+ magnetic ordering in FePO4 has been determined to occur at T = 25.0 K, which agrees well with magnetic measurements reported in the literature. For Fe-3(P2O7)(2), a Schottky anomaly and a four-peak phase transition have been found below 50 K. The thermodynamic functions, magnetic heat capacities, and magnetic entropies of these two compounds have been calculated based on curve fitting of the experimental heat capacity values. The standard molar entropy at T = 298.15 K has been obtained to be (122.21 +/- 1.34) J . K-1 . mol(-1) and (384.12 +/- 4.23) J . K-1 . mol(-1) for FePO4 and Fe-3(P2O7)(2), respectively. (c) 2013 Elsevier Ltd. All rights reserved.