Data were collected from December 2014 to January 2017, with 16 oceanographic cruises, along a transect from the mouth of the Po River (Italy) to the area of Rovinj (Croatia), representative of the northern Adriatic Sea. 6 stations were sampled at 4 depths (0.5 m, 10 m, 20 m and 2 m above the bottom) by Niskin bottles. Water samples for temperature, salinity, pH on total scale, total alkalinity, dissolved oxygen, dissolved inorganic nutrients and chlorophyll a were collected and analysed. Temperature was measured by protected reversed thermometers, salinity by high precision salinometer, pH by spectrophometry with purified m-cresol purple, total alkalinity by open cell potentiometric titration, dissolved oxygen by winkler method, nutrients by spetrophotometric methods, chlorphyll a by acetone extraction and fluorometric detection.