Steel slag is a product of the iron and steel industry, which has been primarily disposed of by landfill. However, today, more than ever before, the imperative of every society that strives to manage more effectively natural resources is to harmlessly recover products in an environmentally friendly way. One of the alternative methods of disposal to the dump is the application of steel slag in agriculture either as a soil improvers or as a fertilizer. Because of its chemical characteristics, steel slags potentially represent a valuable nutrient source, and high levels of calcium and magnesium oxide can be a source of nutrients but also a material for acid neutralization of soil. Therefore, a high-pH steel slag in combination with distric brown acid soil from Smiljan was used in the study. The study was conducted by incubation test in controlled conditions for 16 weeks. The amount of EAF slag was determined on the basis of the results of the previously conducted investigations and was applied at doses of 0,0 g kg-1, 0.5 g kg-1, 1.0 g kg-1, 3.0 g kg-1, 6.0 g kg-1 and 9.0 g kg-1 soil. This paper investigated the influence of steel slag on changes in chemical properties of soil fertility. The obtained results indicate a positive impact on soil fertility indicators such as pH regulation, CEC and the availability of P2O5, Ca and Mg in acidic soil. The obtained results confirm that soil acidity correction can be successfully carried out using steel slag in higher doses than conventional use of natural calcium materials such as dolomite or limestone. Furthermore, by increasing the slag dose, the concentration of mobile aluminum is reduced, the soil base replacement capacity and soil pH are increased as a consequence of the Ca2+ and Mg2+ ion concentration rise in the liquid phase of the soil.