This baseline dataset comprises downcore measurements of total carbon (TC) and total organic carbon (TOC) for a sediment core (MUC) retrieved in the framework of the European collaborative JPI Oceans MiningImpact project onboard R/V SONNE cruise SO268 in 2019. The scientific work during cruise SO268 was part of the second phase of the MiningImpact project (Environmental impacts and risks of deep-sea mining) and is designed to assess the environmental impacts of deep-sea mining of polymetallic nodules in the Clarion-Clipperton Zone (CCZ) in the Pacific Ocean. The analysis was performed on freeze-dried, homogenized sediments using a CS744 LECO instrument (Bruker, Billerica, MA, USA) at the University of Bremen, Germany. In order to obtain TOC contents, samples were pre-treated with 3.4 M HCl and calcium carbonate (CaCO3) contents were calculated.