In the aftermath of Hibs scoring in the 28th minute to make the score 1-1, television pictures showed that the tropical fruit had been thrown on to the field of play.
The coconut is believed to have been chucked from the Roseburn Stand, which houses the away support.
Both sets of fans also set off flares before and during the match. Referee Willie Collum had to stop the game on a couple of occasions to clear the pyrotechnics from the playing surface.
Hibs went on to win the match 2-1 thanks to a brace from Daryl Horgan.