ABSTRACT: Hydrogeochemical modelIing contributes to better knowledge of hydrogeochemical processes in various types of geological media and allows to predict behavior of inorganic substances in space or time. Hydrogeochemical modelIing is able to use different computer programmes and models. This report takes a closer look at the computer program PHREEQC-2, especially its speciation and inverse modelIing and thermodynamic database, which are all parts of this program. The objects of the study are water resources in alluvial deposits of the Torysa River in the locality of Brezovica (Eastern Slovakia).