These data report in-situ ground penetrating radar (GPR) ice thickness measurements at the outlet and the catchment area of Gourdon Glacier on James Ross Island, northern Antarctic Peninsula. Data were conducted in 2017-02-15 and 2018-02-10 with a 25 MHz GPR antenna flown as a sling load by a Bell 212 helicopter. The processing of the GPR data was done in the software REFLEXW v.8.5 (Sandmeier geophysical research) and includes interpolation to equidistant traces, bandpass filtering (10 MHz lower cutoff, 50 MHz upper cutoff), correction to real start time, application of a gain function, and a 2D-finite-difference migration. The travel-time in ice was converted to ice-thickness in meter ["IceThickness(m)"] by applying a constant velocity of 168 m/µs. In case of data from the plateau, a standard correction value for firn and snow of +10 m is applied. The associated error resulting from the GPR measurements ["IceThickness_GPR_error(m)"] and the error additional considering the horizontal positioning accuracy ["IceThickness_Data_error(m)"] are calculated after Lapazaran et al. (2016). Further details about the processing and the error calculation are described in Lippl et al. (in submission). In addition, the surface elevation in reference to the WGS84 ellipsoid [SurfaceElevation(m)] derived from the GNSS signal and the GPR backscatter is included. However, surface elevations can be prone to errors of several meters due to the large foodprint of the radar and the GNSS accuracy.