The compound-specific hydrogen isotopic composition (δ2H) of n-alkanes well reflect hydrological conditions in lake sediments, but the spatial distribution of the δ2H signal of terrestrial and aquatic n - alkanes within lakes is not systematically investigated so far. Therefore, we analyzed compound-specific δ2H of terrestrial and aquatic n-alkanes of 46 surface sediment samples from Lake Khar Nuur, a semi-arid and high-altitude lake in the Mongolian Altai (2,486 m a.s.l.; 48°37'22.9N, 88°56'42.5E). Additionally, we analyzed the terrestrial δ2H signal of 13 topsoils from the catchment. Lake surface sediments were recovered from the lake floor with a Van Veen Grab sampler and topsoils (0-5 cm) were sampled as a mixed samples of three subsamples from each site during a fieldtrip in July 2018. Sample extraction procedure is described in detail by Strobel et al. (in revision). Compound-specific δ2H was analyzed for the terrestrial n-alkane C31 (δ2HC31) in the topsoil and surface sediment samples, whereas δ2H of the aquatic C23 (δ2HC23) was analyzed in the lake surface sediments. One topsoil site is grown by Betula nana (L.) showing C27 as the dominant chain-length, which was target for compound-specific δ2H measurements at this site (δ2HC27). All δ2H measurements were carried out on an IsoPrime visION isotope ratio mass spectrometer coupled to an Agilent 7890A GC via a GC5 pyrolysis/combustion interface operating in pyrolysis mode with a Cr (ChromeHD) reactor at 1050 °C.