In this paper, we apply an original technique for solving the inverse problem of hyperspectral satellite sensing to retrieval of the vertical profile of the HDO/H2O ratio in the Earth’s atmosphere with simultaneous use of thermal and near-IR spectra. This technique is used for the first time to retrieve the relative abundance of the HDO isotopologue (δD) in atmospheric water vapor from measurements of the TANSO-FTS IR spectrometer onboard the GOSAT-2 satellite. The δD values retrieved are compared with data obtained at the ground-based TCCON station in Karlsruhe, Germany. The simultaneous use of satellite spectra of outgoing atmospheric radiation in the thermal range and reflected solar radiation in the near-IR ensures a stronger correlation between monthly average satellite and ground-based δD values than the use of one of these ranges.