Here we present a dataset of pore water chloride and sulfate concentrations of gravity core GeoB21363-1 (GC21) recovered during R/V Poseidon cruise POS499 from the summit of Sartori Mud Volcano (Calabrian Arc, Mediterranean Sea). The gravity core was taken in a plastic foil. Pore water was extracted ex-situ from selected sediment depths on whole round plastic foil using disposable syringes and rhizon samplers. The sampling interval was set to 10 cm. The untreated pore water samples of filtered and unacidified aliquots were stored at 4°C until analysis. Concentrations of chloride and sulfate were analyzed by ion chromatography (IC) using a Metrohm 882 Compact Ion Chromatograph with an 858 Professional Sample Processor at MARUM. Uploaded chloride and sulfate concentrations are given in in Millimol/Liter (mmol/L). Sediment depth is given in meter (m).