This dataset combines Mg/Ca ratios, sea surface temperatures, and stable isotope values (δ¹³C, δ¹⁸O) for planktic foraminifera from IODP Site 392-U1580, which is located at 40°47.15'S, 26°36.41'E, and is 2560 meters deep, covering the PETM period around 56 million years ago. We analyzed the Mg/Ca ratios of Acarinina coalingensis and Acarinina soldadoensis (250-300 m) using ICP-MS at the Department of Geoscience, Utah State University, following specific cleaning methods. Temperatures were calculated using specific methods for each species, adjusting for pH (pre-PETM: 8.05, PETM: 7.8), salinity (35 PSU), and seawater Mg/Ca (2.0 mol/mol) based on the work of Hollis et al. (2019). The data reveal SST warming of 5-8°C across the PETM, from pre-PETM temperatures of 23-27°C to peak PETM temperatures of 28-33°C. Stable isotopes were measured from samples of about 20 shells using standard IRMS, showing a typical negative carbon isotope excursion of -2.5‰.