Abstract <p>Soils of the middle taiga in the south of the Sakha Republic (Yakutia) have been studied. The key sites are located on the interfluve between the Nyuya and Peledui rivers. The soils are acid to strongly acid and have a low organic carbon content. Despite differences in the particle-size distribution and mineralogical composition, a distinctive feature of the parent materials is the high proportion of kaolinite among clay minerals. A somewhat coarser texture of soils at higher elevations ensures good soil drainage and, consequently, the absence of gleyzation. According to the profile-genetic approach of the Russian soil classification system, the soil formed under these conditions is classified as a podzolized podbur. The sequence of soil horizons is complicated by turbation processes. Data on the mineralogical composition of the clay fraction in the soil horizons indicate that this soil is developed from a mineralogically heterogeneous substrate. With a decrease in the terrain elevation, the soils develop on somewhat heavier-textured sediments; the worsening of drainage conditions results in the appearance of gley features in the lower part of the soil profile. Mineralogical data suggest that the soil is developed from a homogeneous material. This soil is classified as a weakly differentiated raw-humus cryometamorphic soil. The differentiation of mineral phases in the soil profile is manifested by the disappearance of the smectitic clay unstable in the acid medium of the upper soil horizons as compared with the parent material.</p>