ABSTRACT: Geophysical methods are widely used in hydrogeological research. Three geophysical methods, together with hydrogeological measurements, were used to identify the primary source of mineral water at the children´s spa in Železné, Slovakia. Geophysical methods of vertical electrical sounding, electrical resistivity tomography and self-polarization enabled to identify the geological-tectonic conditions in the assumed place of original outflow of mineral water to the surface, contacts of various rock types and direction of groundwater inflow. The distinct positive anomaly of the largest gradient of the natural electric field was confirmed by measurements of electric conductivity of groundwater flowing out to the surface and creating small wetted depressions where the electric conductivity reached up to 2370 µS·cm-1.