In the designated snowpits on the MOSAic expedition a 100cm3 sample of snow was measured for density in the field, approximately every 3 vertical centimetres. The same snow volume was melted for salinity measurements and sealed into glass jars onboard Polarstern. As a result, δ18O and δ2H isotope composition was measured at the same intervals as density and salinity profiles, included in the snowpit dataset bundle. These samples were then transported to the WSL laboratory in Switzerland to analyse the stable water isotopes (δ18O and δ2H). This dataset provides details on the date and coordinates of the snowpit event, the height of the sample in the snow profile, and the corresponding isotope composition. This dataset includes the isotopic composition of the samples obtained in the winter months (October 2019 to May 2020). After analysis of the samples, and comparing the values to a parallel dataset (doi:10.1594/PANGAEA.948511), it was identified that our samples needed to be corrected due to evaporative fractionation during sample storage. The corrected values are included in this published dataset and we recommend that future studies using this dataset use these corrected values only. The correction was done by calculating the mean of this dataset to the mean of the parallel dataset and correcting for the difference. As a result, the δ18O was corrected by -6.4‰, the δ2H was corrected by -36.4‰. The new values are located in the columns 'δ18O H2O [‰ SMOW] (Corrected)' and 'δD H2O [‰ SMOW] (Corrected)'. We would like to emphasise that calculations of d-excess values for this dataset need interpreting carefully.