One- and two-dimensional cuprous oxide (Cu2O) nanostructures were fabricated on highly orientated pyrolytic graphite (HOPG) by electrodeposition in CuSO4 at room temperature (25 degrees C) with no additives. For short deposition times, 1D Cu2O single nanocrystals were generally of an octahedral shape with sizes ranging from 50 nm to 400 nm, while 2D Cu2O nanowires with diameters ranging from 100 nm to 300 nm had lengths of more than 100 mu m. With longer deposition times, microwires were found to have diameters ranging from 1 mu m to 2 mu m with lengths up to 60 mu m, while microcrystals were also produced with sizes 1 mu m to 6 mu m. The highly aligned Cu2O nano/microwires were found to be deposited on the step edges of the HOPG substrate. Various crystal morphologies including flower-like and butterfly-like structures, and dendrites and truncated octahedra were observed on the working electrode of HOPG. Some of the morphologies are revealed for the first time by one step electrodeposition and these are confirmed to be single Cu2O crystals. (C) 2013 Elsevier Ltd. All rights reserved.