The feasibility of developing a method for retrieval of the relative content of ¹³СО₂/¹²СО₂ in the atmosphere as a result of solving the inverse problem of satellite sounding of the atmosphere in the thermal infrared range with IASI spectrometers has been studied. In the model experiment, synthetic spectra were used with resolution and noise level characteristic of an improved version of the IASI-NG spectrometer. In computational experiments, it was shown that the vertical profiles of the ¹³CO₂ concentration and the relative ¹³CO₂/¹²CO₂ content in the atmosphere are quite satisfactorily retrieved in the troposphere for the altitude range 2-11 km, which seems promising for future applications of the method suggested.