Brentford got off to a slow start and they never recovered, struggling to come to terms with Leon Constantine and Nathan Lowndes up front and the rock solid visiting defence.
Their only first-half chances came courtesy of set plays, with defender Michael Turner volleying wide from the corner on 19 minutes and Jay Tabb going close with a free kick on 32.
It was Vale however who looked most likely to break the deadlock and they could have had more than one goal.
Michael Cummins was unfortunate to see his 25-yard effort hit the woodwork on 20 minutes, and it was only a matter time before they got the break they deserved.
On 36th minutes the ball set up nicely for Jeff Smith to volley home his first league goal of the season from 20 yards.
Brentford knew they had to change in the second half, and they came out with more purpose after the break.
An error allowed Paul Brooker to break free and he was left with open goal after taking it around the goalkeeper but an extra touch allowed the defence to get back to clear the danger.
In the end Vale could have doubled their lead as both Constantine and Cummins went close in the second half.
Lloyd Owusu was thrown on by Brentford boss Martin Allen to try to add some spice to their attack but he failed to make the desired impact.