Tykes youngster Luca Connell opened the scoring with just a minute on the clock with a superb strike, but Barnsley were soon pegged back when Nathan Smith struck for Vale in the 14th minute.
Barnsley hit back seven minutes later however through Liam Kitching, with Connell assisting, and went in 2-1 up at the break.
Adam Phillips, on off the bench for Barnsley at half time, scored just past the hour mark and the visitors saw out the game to claim a precious three points.
Barnsley boss Duff was not impressed by the pitch at Vale Park and admits he would not want to play on it regularly.
He termed the game a horrible encounter and is thankful that Barnsley were able to show the determination needed to claim the win.
“I thought we were excellent”, Duff was quoted as saying by BBC Sheffield.
“Horrible game, there is no getting away from that. Not a classic.
“That pitch, I wouldn’t want to play on that every week.
“Grit, determination, and little bits of quality. That’s what’s seen us through.”
Barnsley sit in sixth place in League One following the win, while Port Vale, who are 15th, have now not won for seven games on the trot.
