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Abstract: With the aim of investigating the possibilities of magnetotelluric methods for the exploration of potential Enhanced Geothermal System (EGS) sites in the Upper Rhine valley, a 2-D magnetotelluric (MT) survey has been carried out on a 13km long profile across the thermal anomaly in the area of the geothermal power plant of Soultz-sous-Forêts in the winter 2007/08. Despite strong artificial noise, processing using remote referencing and Sutarno phase consistent smoothing revealed significant results from 10 out of 16 sites. Indication for 1-D structures was found in the shortest periods, 2-D effects in the periods up to 40s, and 3-D effects in the long period range. Since 3-D effects were found in the longer periods, 2-D inversion was carried out for periods smaller than 40s. The results of the inversion are consistent with the geology of the geothermal site and distinguish well the sediments from the granitic basement including the structures given by the faults. A conductive anomaly with a resistivity of about 3Ωm has been found at a depth down to 2000m in the area of the Soultz and Kutzenhausen faults, which is attributed to geothermal processes. [Copyright &y& Elsevier]