This dataset contains the n-alkane data from a sedimentary record of an alpine lake (Laguna de Río Seco -LdRS-) located at 3020 masl in Sierra Nevada (southern Spain). This dataset includes the concentrations of the n-alkanes ranging from the C19 to the C35 chain lengths and the hydrogen isotopic composition of the C23, C25, C27, C29, C31, and C33 ones. Different indices have also been calculated to summarise 1) the n-alkane chain lengths: the average chain length (ACL), the carbon preference index (CPI), and the portion aquatic index (Paq), and 2) the hydrogen isotopic composition of the terrestrial n-alkanes (δDwax=δDC29 + δDC31), aquatic n-alkanes (δDaq= δDC23 + δDC25), and their difference ΔDwax-aq(δDwax-δDaq).The n-alkanes were analysed using a GC-FID (Shimadzu 2010) and a GC-MS (Shimadzu QP2010-Plus Mass Spectrometer interfaced with a Shimadzu 2010 GC).Hydrogen isotopic composition of sedimentary n-alkanes was measured with GC-IRMS using a GC-thermal conversion-IRMS system consisting of a HP 6890 GC connected to a Finnigan MAT delta Plus XL mass spectrometer.