Magnetic nanoparticles provide thermo-necrosis therapies but the impact of temperature on the surrounding tissue must be precisely controlled to avoid damage. In this paper, we investigated the design and validation of a differential calorimeter for the evaluation of the specific absorption rate (SAR) of magnetic nanoparticles within colloidal dispersions. Accuracy in the final SAR values was achieved through systematic analysis of the key sources of thermal energy inputs and thermal transport within the environment of the calorimeter, modelled by both a distributed heat equation and a lumped parameter model. This design and the two thermal capacity models used allowed subsequent experimental parameters to be evaluated from the calorimetry protocol reducing uncertainty in the SAR values. Enhanced precision in SAR values would provide additional control of tissue temperatures in thermal necrosis when employing magnetic nanoparticles as a heating source. (C) 2015 Elsevier B.V. All rights reserved.