Presented at the 13th Specialist Meeting on Microwave Radiometry and Remote Sensing of the EnvironmentAquarius brightness temperature data are used to calculate sea ice thickness in the Arctic region. The method is based on the inversion of a radiative transfer model for ice-covered sea. Using this technique, the initial sea ice thickness values retrieved from Aquarius data are compared to the SMOSIce Data as well as to estimates from NASA's Operation IceBridge. The results show similar trends between the SMOS- and Aquarius-derived sea ice thickness, however the Aquarius estimates tend to be higher and noisier than the corresponding SMOS values. The accuracy of retrieved Aquarius ice thickness is possibly influenced by uncertainties in the ancillary input parameters and by the coarser resolutions of Aquarius.