The utilization of mineral wastes from the power plant such as fly ash and bottom ash and from incineration waste treatment plant such as fly ash and air pollution control residue, is a challenge from the point of view of environmental engineering practice. This type of waste is used in mining, construction, road construction, as well as in agriculture, for example, as a raw material for mineral fertilizers. One of the uses of waste is reclamation. However, due to the physical and chemical properties of such waste, it may have a negative impact on the soil and water environment. Fly ash from the combustion of hard coal, lignite, agro and forest biomass and solid residues from the combustion of sewage sludge were studied. The chemical composition, leachability and phytotoxicity test were determined. The analysis of the tested ashes showed a high variability of the properties, depending on the type of fuel combusted. Fly ash contained macro- and micro-nutrients, indicating its fertilising properties and therefore its usefulness in the reclamation of degraded areas. On the other hand, fly ash from agro biomass and flue gas desulfurization products from the combustion of waste sludge showed a phytotoxic effect on the test plant Lepidium sativum, which is related to their high content of sulphates and chlorides.