The Neodymium (Nd) isotopic signature (εNd) has been widely used as a proxy to reconstruct past ocean circulation. Recently it has been increasingly questioned which archives can be reliably used to extract authigenic εNd used for the reconstruction of past ocean circulation and under which environmental conditions bottom seawater εNd are altered and the original water mass signature is overprinted. Pore waters of marine sediments are the key environment in which early diagenetic exchange processes between seawater-derived Nd and terrigenous solid phases take place. This dataset contains Nd isotope compositions of bottom seawater from the abyssal Atlantic and Pacific Oceans, focusing on the behavior of the Nd isotope composition in oxic deep-sea sediments during early diagenesis.Samples for the Atlantic were collected during cruise MSM96 in 2020 and for the Pacific during cruises SO268 in 2019 and SO295 in 2022. Seawater samples were taken with NISKIN or GoFlo bottles attached to a CTD water sampling carousel or a bottom water sampler. Samples were filtered using 0.8/0.2 µm Acropak capsule filters for the dissolved fraction (<0.2 µm). Samples from the Atlantic were subsequently filtered through either 0.015 µm nuclepore membrane filters (Whatman; under gas pressure) for the soluble (<0.015 µm) fraction or ultrafiltered using a Millipore Pellicon 2 tangential flow ultrafiltration system with a 10 kDa nominal molecular weight cutoff (truly dissolved fraction <10 kDa). Samples for the Pacific were additionally pooled in the lab to combine several depths of the bottom water sampler for sufficient volume. Seawater was preserved by acidification to ~ pH 1.8 with concentrated ultrapure HCl.Neodymium was purified using first BIORAD AG50W-X8 resin, followed by Eichrom Ln-spec resin. Samples were measured by MC-ICP-MS.