The present study was conducted during the Arctic Century 2021 Expedition, which took place from 5 August to 6 September 2021 with the icebreaker RV "Akademik Tryoshnikov" and was jointly organized by the Helmholtz Centre for Ocean Research Kiel (GEOMAR) in Germany, the AWI in Germany, the Swiss Polar Institute (SPI) and AARI in Russia. In the frame of the Arctic Century expedition, new shallow firn cores of up to 6.5 m depth were repeatedly drilled on Akademii Nauk (AN) ice cap (Severnaya Zemlya, SZ) and on Windy Ice Dome (WD, Franz-Josef-Land, FJL) to gather new high resolution proxy data from the Russian High Arctic. Additionally, University Ice Cap (UN) on October-Revolution Island has been cored for the first time. The dataset comprises the stable water isotope data of snow profiles from Windy Ice Dome (WD: WD-SP), Franz-Josef-Land (FYL), Akademii Nauk (SZ: SZ-SP) and University (UN: UN-SP) ice caps, Severnaya Zemlya (SZ). The stable oxygen (δ18O) and hydrogen (δD) isotope composition of all core samples (n=902) were determined at the ISOLAB facility of AWI in Potsdam (Germany). A Picarro L2130i cavity ringdown spectrometer (CRDS) was used for all ice-core and snow pit samples with an analytical precision of ±0.08‰ for δ18O and ±0.5‰ for δD. The stable water isotope composition was reported in per mil (‰) versus Vienna Standard Mean Ocean Water (VSMOW2). The second order parameter deuterium excess (d xs) was calculated as d xs = δD – 8 * δ18O.