Description: Sediment community oxygen consumption is an established measure of benthic activity and recommended by the International Seabed Authority for baseline investigations as part of exploration activities (document ISBA/25/LTC/6). It addresses rates of organic matter remineralization as a key function of seafloor ecosystems. In 2019, oxygen flux measurements were carried out at locations approx. 1000 km apart in the Clarion Clipperton Fracture Zone (CCZ) within the German and Belgian exploration license areas. Rates of total (TOU) and diffusive oxygen uptake (DOU) were quantified in situ with benthic chambers and microprofilers manipulated by remotely operated vehicle (ROV). The study was carried out in the framework of the European collaborative project MiningImpact under the Joint Programming Initiative Healthy and Productive Seas and Oceans (JPI Oceans). The primary aim was to settle a baseline in preparation of a subsequent assessment of the environmental impacts associated with the first test of a manganese nodule collector pre-prototype in international waters. In both license areas, replicate measurements were obtained at different sites across several kilometers distance. Based on this extensive data set, the presentation aims to assess the requirements (e.g., in terms of replication, relevant spatial scales, methodology) for oxygen uptake observations in the context of environmental baseline studies. Lateral variability in fluxes is addressed as well as differences between total and diffusive fluxes and relations to other biogeochemical data obtained in sediment and pore water samples (e.g., nutrients, organic matter, chloroplastic pigments). In addition, first data on immediate effects of the recently performed pre-prototype collector test on oxygen distribution in the upper sediment layer are presented.