A self-potential survey was carried out in the Kestanbol area in order to investigate the fault zones that might be associated with geothermal activity. Two fault zones, which could be interpreted as planes electrically polarized by geothermal activity, have been detected by compilation of a self-potential map. A resistivity survey, using the Wenner configuration, was able to identify the geoelectrical structures that are caused by different rocks with variable degrees of fracturation and also affected by geothermal activity. The resistivity maps and two-dimensional geoelectric models indicated a good conductive region (<10 ohm-m) in the southwest part of Kestanbol. On the basis of the results of both methods, a new location is proposed for drilling in this conductive zone. (C) 1999 CNR, Published by Elsevier Science Ltd. All rights reserved.