In this work, an effective approach to synthesize large-area Cu(2)S hierarchical nanotree arrays is presented: Cu nanowire arrays synthesized via template-assisted electrodeposition are used as precursors for the self-growth of branched Cu(2)S nanotree arrays by a gas-solid reaction in H(2)S atmosphere at room temperature. The branched Cu(2)S nanotrees with a high aspect ratio are vertically aligned over the Au film surface, forming a nanoscale 'forest'. Electron microscopy studies reveal that the treelike branched nanostructures are composed of an end-capped tubular Cu(2)S trunk and radially organized Cu(2)S nanorod branches over the trunk. A formation mechanism of the hollow trunk and the nanobranches is proposed on the basis of experimental observations.