SMOS 2008 Validation Rehearsal Campaign comprised a set of flights on the TKK's Skyvan to simulate the same conditions of the validation of ESA's mission SMOS after the launch. Two L-band radiometers, TKK's HUT-2D and DTU's EMIRAD, and the ICE/IEEC-CSIC's GOLD-RTR GNSS-R instrument were employed for the extraction of soil moisture and ocean salinity. For the first objective, several flights were done over four different sites with soil moisture stations, calibration lakes and in-situ ancillary data: Rur/Juelich, Danube, Vercors and Valencia. They were conducted before sunrise to avoid contamination of the radiometric measurements due to the L-band emissions of the Sun. The sea surface salinity measurements were performed during the displacements over the Baltic and Mediterranean Seas. This campaign was funded by ESA and comprised the participation of many other institutions: UVEG, LMU, DLR, FZJ, LOCEAN, INRA-EPHYSE, CESBIO, IFREMER and ICM-CSIC.