Compound-specific hydrogen and oxygen isotope analyzes on leaf wax-derivedn-alkanes (delta H-2(n-alkane)) and the hemicellulose-derived sugar arabinose (delta O-18(ara)) are valuable, innovative tools for paleohydrological reconstructions. Previous calibration studies have revealed that delta(2)H(n-alkane)and delta(18)O(ara)reflect the isotopic composition of precipitation, but - depending on the region - may be strongly modulated by evapotranspirative enrichment. Since no calibration studies exist for semi-arid and arid Mongolia so far, we have analyzed delta(2)H(n-alkane)and delta(18)O(ara)in topsoils collected along a transect through Mongolia, and we compared these values with the isotopic composition of precipitation (delta(2)H(p-WM)and delta O-18(p-WM), modeled data) and various climate parameters. delta(2)H(n-alkane)and delta(18)O(ara)are more positive in the arid south-eastern part of our transect, which reflects the fact that also the precipitation is more enriched in(2)H and(18)O along this part of the transect. The apparent fractionation epsilon(app), i.e., the isotopic difference between precipitation and the investigated compounds, shows no strong correlation with climate along the transect (epsilon(2H n-C29/p)= -129 +/- 14 parts per thousand, epsilon(2H n-C31/p)= -146 +/- 14 parts per thousand, and epsilon(18O ara/p)= +41 +/- 2 parts per thousand). Our results suggest that delta(2)H(n-alkane)and delta(18)O(ara)in topsoils from Mongolia reflect the isotopic composition of precipitation and are not strongly modulated by climate. Correlation with the isotopic composition of precipitation has root-mean-square errors of 13.4 parts per thousand for delta H-2(n-C29), 12.6 for delta H-2(n-C31), and 1.2 parts per thousand for delta O-18(ara), so our findings corroborate the great potential of compound-specific delta(2)H(n-alkane)and delta(18)O(ara)analyzes for paleohydrological research in Mongolia.