A device for hanging an object on a supporting structure such as a wall comprises a one-piece backing plate having a plurality of co-planar bars extending between co-planar side rails and forming slots between the bars, with the backing plate including offset shoulders for offsetting the planes of the side rails and the bars to provide a space between the bars and the wall when the backing plate is affixed to the wall. A one-piece hook for supporting the object includes a planar body portion and a protrusion forming with said body portion a U-shaped receptacle for accepting an object to be mounted to the wall. The hook also includes an L-shaped hook retainer at one location on the body portion for removably fitting into a first slot with the upright of the "L" extending behind the bar adjacent to the slot, and a hook support finger at another location on the body portion for removably fitting into a second slot disposed below the first slot and bearing against the wall when the backing plate is affixed to the supporting structure.