Mine water from both operating and abandoned mines can be used for individual space heating projects, district heating/cooling systems or for preheating air for mine ventilation. Examples of such applications are already known from Canada, US, Netherlands, UK, and Spain. The Upper Silesian Coal Basin (USCB) in Poland, where 34 of 65 hard coal mines have been abandoned since 1989, represents a potentially large opportunity for mine water heating schemes. This paper describes the mines from Bytom (northern USCB) as a potential location for ground source heat extraction projects. Hydrogeological and hydrogeochemical studies of pumped waters have been carried out in order to better understand the potential of the Bytom heat resource. The monitoring program is still ongoing, but initial results compare favorably with existing mine water geothermal source systems where water temperatures are comparable or lower than those found at Bytom. Initial hydrochemical and isotope data demonstrate stability in water composition at most of the monitoring points. These data elucidate the hydrogeological cycle during active dewatering and provide a baseline for understanding the geothermal behavior of the system, which is crucial for optimizing heat extraction. Preliminary results also reveal very stable mine water temperatures in the pumped, and hydrologically connected, Szombierki system and suggest remarkable stability in the characteristics of the main hydrothermal reservoirs. (C) 2016 Elsevier B.V. All rights reserved.