A door jamb mountable hinge (14) for supporting folding doors (10). The assembly (14) comprises an L-shaped bracket (16) having a mountable portion (18) and a support portion (20). The mountable portion (18) is attached to the door jamb (12) and the support portion (20) supports the adjustable hinge arm support (30). The hinge support arm (30) supports a pivotally mounted folding door (10) which allows the bracket (16) to be mounted behind the plane of the closed door (10) and out of view. The hinge support arm (30) is threadily secured in position via a bolt (38).