Dataset contains grain size data collected in the Romanian shelf, during a cruise onboard R/V mare Nigrum, conducted in July 2024, within the national project "Improving the monitoring program for the Romanian Black Sea self in order to increase the capacity to assess and predict the impact of multistressors on marine ecosystem services" PN 23 30 01 03. Thirty-two sampling stations were performed for grain size investigations by the GeoEcoMar team. Sediment samples were collected using Van Veen grab sampler and Multicorer MARK II-400 and analyzed for grain size composition and textural parameters of the sediments, with Mastersizer 2000E Ver. 5.20 (MALVERN) equipment in the GeoEcoMar lab.