The formation of plant communities and soils on ash dumps reduces their negative impact on the environment however, there are little data on the properties of Technosols formed on the ash substrate during spontaneous vegetation. Comprehensive geobotanical and soil studies were carried out on Sredneuralskaya thermal power plant (SUTPP) fly ash dump area spontaneously overgrown with herbaceous vegetation, as well as on background areas with secondary post-forest meadows. The purpose of the study was to identify the features of soils formed on a 50-year-old ash dump under meadow communities in the southern taiga conditions of the Middle Urals. It was revealed that in the process of the primary succession on the ash dump, herb-grass meadow communities have been formed. In general, the ash substrate turned out to be heterogeneous in its physicochemical properties. However, the young soils formed in its upper layer (Technosols) are similar in morphological structure and features of profile differentiation in terms of the content of organic carbon, total nitrogen, mobile forms of phosphorus and potassium, exchange cations of calcium and magnesium (with the maximum accumulation of the studied elements in the humus horizon) as well as in the reaction of the medium. In comparison with the background soils, the content of most biogenic elements in the young soils of the ash dump is significantly lower. The data obtained will contribute to the establishment of soil formation patterns on technogenic substrates and, ultimately, will allow influencing the transformation of technogenic ecosystems. Since there is little information on the properties of Technosols formed on ash dumps during spontaneous succession, the data obtained will help to establish the patterns of soil formation on technogenic substrates, and ultimately will allow influencing the rate of soil formation.