SuperGreg, on the opening day of long-course swimming, dominated the event in 1 hour 49 minutes and 12.2 seconds, leaving behind world silver medallist Marc-Antoine Olivier and Doha world champion Kristof Rasovszky.
Italy’s Domenico Acerenza finished fourth.
Paltrinieri, 29, from Carpi near Modena in Emilia-Romagna, is a multiple Italian, European, world and Olympic champ.
He competes in both short course and long course events and has won races spanning 800m and 10km.
ANSA