Wastes resulting from all human activities pose one of the most crucial problems of the environmental protection and one of the most difficult tasks facing environmental engineering. In spite of the existing proved methods of their neutralization such as burning, composting and storage, new solutions are still being sought. Among new methods gaining in popularity is the use of microwave energy for decomposing/ /neutralizing such wastes as medical scraps, highly contaminated soil, scrap rubber or asbestos. In addition to being considered cheap and efficient, the method contributes to developing technological ways of its application. The present paper shows the results of investigations on the use of microwave energy to neutralize such wastes as spent carbon sorbents and catalysts containing heavy metals and sludge. It has been proved that the microwave mineralization of spent carbon sorbents and catalysts is able to decompose at a heat the carbon matrix completely as well as all organic impurities present in such wastes, and to transfer metals to an acid solution. As the volume of the acid solution used in the process is inconsiderable, the concentration of metals is high, which favours their quantitative recovery (e.g. as regards noble metals) or their separation by precipitation. The method is particularly useful in recovering noble metals from spent powdery catalysts of the activated carbon-noble metal type. As regards sludge, investigations on the effects of the energy of microwaves of different power on sludge and on the extraction removal of heavy metals from it were carried out. The results account for suggesting a relatively simple method of lowering the content of metals in sludge and their further use or safe storage.