Accumulation of soil organic carbon together with changes in thickness of humus and fermentation layers, pH bulk density and total phosphorus content were studied in chronosequence of 15 plot (2–41 year old) on colliery spoil heaps, overgrown by spontaneous vegetation. Heaps were formed by alkaline (pH about 8) tertiary clay material. Only scarce herb and grasses occur in sites 2–14 years old, 15–25 year old sites were covered by willow (Salix caprea) shrubs and tree (Betula sp. and Populus tremula) dominated in 25–41 year old sites. Even youngest sites contain about 4% of organic carbon. Thickness of organic soil horizons and content of carbon in mineral soil increased during succession. Thickness of fermentation layer peaked in 15–25 year old sires, humus layer appears on 25 year old sites and its thickness gradually increases with plot age. Accumulation of organic carbon during the first 40 years of succession in average 93g m–2 year–1. As a consequence of organic matter accumulation in soil, bulk density of soil and soil pH gradually decreased with succession age. Content of total phosphorus did not change with succession age.