International audienceThe purpose of this study was to develop an inversion approach to estimate soil moisture over Grassland areas by coupling SAR and optical data. A time series of radar (TerraSAR-X and COSMO-SkyMed) and optical (SPOT 4/5, LANDSAT 7/8) images were acquired over an agriculture region in southeastern France. In most cases, the optical and radar images were not separated by more than four days. Ground-truth measurements of volumetric soil moisture and vegetation descriptors were performed simultaneously with image acquisitions