The geothermal (25-82 degrees C) waters of the shallowest groundwater system of the Province of Vojvodina (northern Serbia), part of the Pannonian Basin, are characterized by their elevated gas content (above 1 N m(3)/m(3)) with a high methane fraction (on average, about 93.3% of total gases). These methane-containing waters are particularly abundant in Central Backa in the NW part of the province. Reported are the amount and composition of the gases in the thermal waters produced by 23 boreholes across Vojvodina drilled from 200 to 1200-m depth. Because of the high methane content, and the possibility of explosion, some of the gas has to be removed before the thermal waters can be safely utilized. A special device (Geomix) to reduce the methane content in the waters down to a permitted level was designed and tested. (C) 2009 Elsevier Ltd. All rights reserved.