Ashes from various Polish coal-fired power plants were analysed in this investigation as the source material for preparing simulants of lunar regolith. The chemical and phase constituents were the most important parameters used to describe these ashes. The second parameter was particle size and morphology, specifically characterising technological properties such as flowability or density. The final element of the investigation was related to the characterisation of thermal properties. Differential thermal analysis yields information on phase transitions, melting temperatures and other characteristic temperatures of stimulants. Thermogravimetry with Fourier transform infrared analysis provides information on evolved gas species and their evolution temperature profiles.