This dataset includes concentrations of Particulate Organic Carbon (POC) and Particulate Organic Nitrogen (PON) from the sea water and sea ice. Samples were collected in August and September 2021 as part of cruise 2021710, JC2-2, in the northern Barents Sea and the Arctic basin as part of the Nansen Legacy project. Sea water was sampled at seven different stations using Niskin bottles attached to a rosette onboard R/V Kronprins Haakon. At three of these stations we also conducted sea ice work and sampled sea ice cores (gear: Kovacs ice corer 9cm) and under-ice water (gear: Niskin bottle) from a hole in the ice and water from meltponds (gear: bucket) for POC/PON analysis. For sea water water triplicate subsamples (1000–9500 mL) were filtered on pre-combusted Whatman GF/F filters, the limited volume of melted sea ice allowed only one but occasionally triplicates subsamples (290-2350 mL). Filters were stored at −20 °C, and analyzed within 1 years on a Leeman Lab CHN Analyzer according to the procedures described by Reigstad et al. (2008). Presented are averaged POC and PON values (in mg m-3), standard deviations and the C:N ratio. PON values < 3x blank values were excluded from the dataset.