This data set presents dissolved copper (dCu) and copper-binding ligand (L) data for deep-sea pore waters in the Peru Basin, south east equatorial Pacific Ocean and the Clarion Clipperton Zone (CCZ) in the central equatorial Pacific Ocean. Samples were taken during cruises SO242, SO262, and SO268 using rhizons with a pore size of 0.12-0.18 µm. Several depths from one multicorer liner were pooled to get sufficient sample volume. dCu was determined by either ICP-MS analysis in kinetic energy discrimination mode or by competitive ligand equilibration–adsorptive stripping voltammetry (CLE-AdCSV). Cu speciation in the samples was also determined with CLE-AdCSV using salicylaldoxime (SA) as the added ligand. For each titration, the concentration of complexing ligands ([L]) and corresponding conditional stability constants (logK) were determined using the fitting software named ProMCC. The free copper ion (Cu2+) and bioavailable Cu' (Cu2+ + inorganic copper) were also calculated. Data was fitted using both the one-ligand and two-ligand complete complexation-fitting model. The model with the best fit and thus the least fitting error was used for data interpretation - this was always the one-ligand model. Side reaction coefficients and stability constants of SA of each sample were provided by van den Berg's ion-pairing model for seawater (EXCEL worksheet - ion-pairing model for seawater, written by C.M.G. van den Berg in 2014) using sample specific salinity values measured in the lab, a SA concentration of 5 µM, an ambient temperature of 21˚C, and a pH of 8.1.