The research results of some aspects of soil chemical composition in the surroundings of the biggest pit, acid reservoir located on Łuk Mużakowski (SW Poland) are presented. Samples were taken every 1m depth, from three 25m deep, boreholes and content of TOC, iron, calcium and aluminium was analyzed. Boreholes were located in the closest neighbourhood of the reservoir, one on side of groundwater inflow, two others on the opposite site. Watertable in each places was confined and groundwater had the chemical composition typical for AMD. Geological structure consisted mainly from sand and clay with sand and brown coal layers. ; Concentrations of TOC varied from trace amounts to 22,65% dry mass dependently on geology. Soils under research contained high amounts of iron and were poor in calcium. Aluminium concentrations were imperceptibly lower than iron ones and varied from 0,27 to 7,45% dry mass. The following conclusions were formulated: chemical composition of soils stayed under influence of interactions with AMD, the content of iron and calcium may be the result of secondary minerals precipitation form AMD, lack of calcium created conditions favourable water and soil acidification.