The article reports the conducted analyses of certain chemical parameters characterising the sediments of Poland’s Besko Reservoir. Specifically, determinations concerned the pH value, percentage organic matter (OM), total organic carbon (TOC), total nitrogen (TN), carbonates (CO32-), total phosphorus (TP) and its fractions, as well as heavy metals (Fe, Al, Cr, Cu, Ni, Cd, Zn, Mn). The sediments have a slight alkaline reaction, with pH values correlating positively with the high content of carbonates. The sediments have low organic matter content, while organic carbon accounts for about 30% of OM. The values for the C:N ratio point to an allochthonous origin for organic matter. The analysis of phosphorus fractionation showed that inorganic phosphorus (IP) is predominant at every research station. The lowest percentage for a fraction was in turn obtained for NAIP. This testifies to a slight anthropogenic impact of the catchment area. The sediments can be classified as of the 2nd purity class (according to PIG), due to their highest concentration of chromium. According to Müller’s classification, the sediments can be classified as purity class 3 (i.e. with moderate contamination). The values noted for the EF coefficient confirm a very strong enrichment by chromium ions. In addition, chromium, copper, nickel and cadmium have a negative effect on aquatic organisms. The results show that the sediments can be used for example in building and maintaining hydraulic structures.