Copper (Cu) is a bio-essential trace metal involved in many phytoplankton metabolic processes. In seawater, its bioavailability is controlled by the formation of organic complexes with binding ligands which also controls the toxicity of free cupric ion (Cu²⁺). Despite this key role, information about Cu speciation is scarce, especially in the Arctic Ocean. However, this oceanographic region is essential to understand the copper biogeochemical cycle. This dataset contains the results of Cu complexation measurements in station depth profiles sampled in Fram Strait and Greenland Shelf. Samples were collected during GEOTRACES expedition GN05 (PS100) between 21 July and 1 September 2016, following GEOTRACES guidelines (https://www.geotraces.org). Copper binding ligand concentrations (LCu) and conditional stability constants (logKcond) were measured by Competitive-Ligand Exchange Adsorptive Cathodic Stripping Voltammetry (CLE-ACSV) using Salicylaldoxime (SA) as competitive ligand (Campos and van den Berg, 1994). The concentration of dissolved copper has been reported by Krisch et al. (2021) (doi:10.1594/PANGAEA.933431).