Soil moisture is one of the most important indicators for drought monitoring and is a key parameter in hydrology and natural risk assessment. Active-microwave remote-sensing techniques have already shown their potential for soil moisture mapping whatever the weather conditions. Most studies on soil moisture mapping were carried out using C-band SAR data. However, several drawbacks have been identified and were linked to the low temporal frequency of SAR acquisition, surface roughness vegetation-related signal corrections and the difficulty in transferring the approach to another study site. With its high sensitivity to soil moisture and low sensitivity to surface roughness, the TerraSAR-X sensor (X-band) has the potential to overcome some of the limitations mentioned above. Moreover, its high temporal and spatial resolutions are key features which facilitate the development of operational products. The objective of the present study is to investigate the potential of TerraSAR-X mono polarization for bare soil detection and soil moisture mapping. This study was carried out on the Orgeval catchment (France) using images and in-situ measurements over bare agricultural plots in 2009 and 2010. The soil moisture estimation algorithm has been developed for bare soils for two configurations of TerraSAR-X (HH-25°, HH-50°) using a database with a huge range of soil surface conditions (dry to wet and smooth to rough conditions) acquired in 2009. Then, the inversion algorithm was validated in using TerraSAR-X images acquired in 2010. To identify bare agricultural plots, the first TerraSAR-X image acquired in 2010 (March 1, HH-50°) was used in using a simple threshold on the mean backscattered signal. Results showed a good accuracy of bare soil mapping. Moreover, the comparison between soil moisture contents estimated from TerraSAR data and those measured from in situ campaigns shows good estimation of soil moisture, with a mapping accuracy (RMSE) of 3.2% and 4.3% for incidence angles of 25° and 50°, respectively.