Modulated temperature calorimetry has been carried out on silver iodide using a novel apparatus, which could expose the sample to conventional heating, microwave heating or any combination of the two. A 20 degrees C reduction in temperature for the beta-alpha phase transition was achieved when the sample was irradiated with microwave energy. Quasi-isothermal studies also suggested that silver iodide could be transformed between states without changing its temperature when irradiated with microwaves. This study suggests a genuine 'microwave effect' is occurring in this material. (c) 2006 Elsevier B.V. All rights reserved.