Hazardous wastes, such as asbestos-containing wastes (ACW) or fly ashes (FA) resulting from municipal solid waste incineration, can be converted into inert materials using plasma torch technology. Depending on the origin of the wastes and on the cooling conditions, the materials obtained at room temperature can be glassy or partially crystallized. The aim of this work is to investigate the potential valorisation of such inertized products as sensible heat material for high temperature thermal storage in thermodynamic solar power plants. Thermal stability and optical properties have been studied from room temperature up to 1000 degrees C by infrared spectroscopy, differential scanning calorimetry and X-ray diffraction. All the studied materials are stable and present high total emissivity within the experimented temperature range. Their physical and chemical characteristics make of them to be good candidates for sensible heat storage materials. (C) 2011 Elsevier Ltd. All rights reserved.