The home side were forced to play the entire second half a man down after goalkeeper Simon Royce saw red for a deliberate handball shortly before half-time.
Gillingham handed a first start to teenage striker Luis Cumbers and it was he who fashioned the first chance of the night on 16 minutes when he fired over from the edge of the area after good work by Adam Miller.
The game soon descended into a series of mis-placed passes and disjointed play, but Craig Davies threatened to wake the supporters on the half-hour with a thunderous 35-yard drive that crashed back off Royce's post.
The game finally came to life when, in the 38th minute, Royce charged out of his area to meet Neal Eardley's through ball but only succeeded in blocking Davies' shot with his arm leaving referee Iain Williamson with little option but to dish out a red card.
Skipper Andrew Crofts was the man sacrificed for replacement keeper Derek Stillie and the substitute could only watch as Eardley curled the resulting free-kick onto the crossbar and over.
Davies wasted a glorious chance to edge the Latics ahead after the break when he blazed over from ten yards, while at the other end Gillingham had strong claims for a penalty after Stefan Stam clumsily challenged Cumbers just inside the area.
As the second half progressed, Oldham slowly began to make their numerical advantage tell with Lee Hughes beginning to pose problems with his movement and trickery.
The former West Brom man forced Stillie into a smart stop from close range on 80 minutes and then provided a perfect cross that Davies could only glance onto the post.
It was not to be Davies' night as, with only a minute remaining, he blazed Jean-Paul Kalala's cross over from barely three yards out as the Gills held on for the first goalless draw at Priestfield since October 2005.