During the AO2024 expedition (19 July to 12 August 2024), Melosira assemblages were collected using a handheld net at two sampling sites in the Amundsen Basin. Pelagic particulate organic matter (PPOM) was sampled at 13 stations spanning the Amundsen and Nansen Basins as well as the Gakkel Ridge, using Niskin bottles mounted on a CTD rosette. Between 3 and 6.5 L of seawater were filtered through GF/F filters. Ice-associated POM was obtained using a Kovacs 9 cm ice corer at one station each in the Amundsen and Nansen Basins; the bottom 10 cm of each ice core were melted with the addition of filtered seawater and filtered onto GF/F filters.Lipids were extracted from freeze-dried samples following the method of Folch et al. (1957), using a dichloromethane/methanol mixture (2:1, v/v) in a sonication bath. Thereafter, lipids were saponified with 20% potassium hydroxide in water/methanol (1:9). Sterols were extracted with hexane, purified by open-column chromatography with SiO2 and eluted with methanol. Sterol fractions were derivatized using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). Sterols were analyzed with gas chromatography–mass spectrometry (Agilent 7890B, Agilent Technologies), equipped with a DB-1ms column (30 m length, 0.25 mm internal diameter, 0.25 μm film thickness) and an Agilent 5977A MSD, following Stein et al. (2025). The temperature program ranged from 60°C to 320°C. Sterols were quantified using an internal standard (androstanol).Sterol analysis was conducted to complement datasets on fatty acid proportions and fatty acid stable isotope compositions. Collectively, the datasets enable a detailed characterization of the biochemical composition of different algal assemblages across the central Arctic Ocean.