At the 2008 Summer Olympics in Beijing, Salcius qualified for his second Lithuanian team in the men's 100 m butterfly. He cleared a FINA B-standard entry time of 54.16 from the European Championships in Eindhoven, Netherlands. Unlike his previous Games, Salcius posted his lifetime best and broke a Lithuanian record of 52.90 seconds to touch the wall first in heat 3 by less than 0.18 of a second ahead of three-time Olympian Jeremy Knowles of the Bahamas. Salcius failed to advance again into the semifinals, as he placed thirty-fourth out of 66 swimmers in the prelims. He also tied his position with Canada's Joe Bartoch.