First-half goals from Nathan Smith and Mitch Clark condemned Latics to a defeat at Boundary Park.
Zak Dearnley made it three goals in as many games, but Latics couldn’t find another goal to earn a share of the points.
The visitors got out of the blocks faster at Boundary Park, however it was Latics who had the first chance of note with Dearnley showing great vision finding Conor McAleny who showed good feet to get past his man, but was unable to get his shot off.
The Valiants had the better of the early exchanges with Tom Conlon and Theo Robinson both having efforts on goal before the deadlock was broken in the 12th minute with Nathan Smith rising highest to head home unchallenged.
The inform Dearnley looked to immediately restore parity but his low effort was comfortably saved by Scott Brown in the Port Vale goal.
Smith should have doubled his tally for the afternoon when again he found himself with plenty of room in the Oldham box, but this time his headed effort sailed just wide of the mark.
On the half-hour mark, Latics had a half-chance to level the scores as there was somewhat of a scramble in the Port Vale box but Dearnley’s effort was eventually blocked.
In the 39th minute, John Askey's side scored to give them a two-goal cushion that their dominant display deserved. Mitch Clark cut inside from the right before curling a left-footed effort into the far corner giving Ian Lawlor no chance.
It could have got worse for the hosts just before the interval and it would have been 3-0 if it hadn’t been for a brilliant block by Harry Clarke.
Latics found a way back into the game less than five minutes after the break. Dylan Bahamboula headed the ball goalwards and Dearnley ensured the ball found its way into the back of the net to make it three goals in three games for the forward.
Vale nearly regained their two-goal cushion just after the hour mark, Christian Montano’s low cross found its way to David Amoo but Lawlor was on hand to make the save from point-blank range.
Carl Piergianni missed a golden opportunity to level the scoring, but he headed wide from a Danny Rowe corner.
Latics continued to push for a goal to bring them level and again it was a Danny Rowe corner that caused Vale problems with Clarke’s looping header having to be cleared off the line from a visiting defender.
An equalising goal evaded the hosts despite late pressure including an effort from distance from Bahamboula that stung the hands of the Vale stopper.
Oldham Athletic XI – Lawlor (GK), Clarke, Piergianni ©, Whelan (Keillor-Dunn 77’), Rowe, Barnett (Borthwick-Jackson 46’), McAleny, Dearnley, Bahamboula, McCalmont, Hamer (Fage 46’)
Substitutes – Bilboe (GK), Grant, Jameson, Ntambwe.
Goals: Dearnley 50’
Port Vale XI – Brown (GK), Joyce, Legge ©, Smith, Worrall, Conlon, Montano (Rodney 88’) Robinson (Pope 81’) Clark, Amoo (Fitzpatrick, 72), Burgess.
Substitutes – Visser (GK), Cullen, Brisley, Whitehead.
Goals: Smith 12’, Clark 39’
Referee – Martin Coy