Hungerford threatened early, with James Clark running at the heart of the Slough defence before testing Jake Somerville, and shortly after James Pilling side footed a shot into the Slough keeper’s arms.
Slough, in response, offered a James Dobson shot which flew well wide of the post, and Ben Edwards lifted a shot well over the bar after Eddie Smith knocked the ball down.
Edwards blasted another shot wide from 25 yards after doing well to win possession, and with Slough on top, Scott Harris dragged a shot wide from a good position.
The best effort of the half came as Dobson’s long range effort came back off the crossbar with Paul Strudley beaten.
Eddie Smith was forced off with an injury late in the first half, but Slough took a lead into the half-time break thanks to Adrian Sear’s first goal for the club. Sear was on hand to head home from close range after a Dobson corner was not cleared properly by Hungerford.
However, the visitors started the second half strongly and were quickly level when a defence-splitting pass from James Clark found O’Brien, who brought the ball in from the left and fired in via the underside of the bar.
The goal immediately provided Hungerford with more confidence, and went close to finding the target again as a corner flew all the way across goal without getting a vital touch.
Slough were fortunate to avoid going behind when a Lee Smith shot was cleared off the line after Somerville missed his punch, and then from the resulting corner, the ball rebounded back off the post and away to safety.
With Hungerford well on top and piling on the pressure, Somerville made another save from a header and the visitors put a shot wide.
But Slough were powerless to prevent the visitors from going ahead seven minutes from time, a blow from which the Rebels could not recover. O’Brien was again the Hungerford hero, the midfielder drilling into the bottom corner after working his way past Sean Fraser and into the Slough box on the left hand side.
Slough’s best efforts to find an equaliser were thwarted, with Harris firing over with Sear perhaps in a better position to receive the ball, but the Rebels were unable to find a path to goal.
Hungerford Town Line up
Paul Strudley, Gary Horgan, Diak John (c), James Rusby, Matt Day, James Pilling, James Clark, Matt Collins, Harry Goodger, Lee Smith, Alan O'Brien. Subs: John Munday, Scott Rees, Isaac Oset-Tutu, Jon Boardman, Brendan Norris.