ZnO nanorods were electrochemically synthesized using various resistivities of Si substrates. With the increase of Si wafer resistivity from 0.01-0.02 to 110-150 Omega cm, the average diameter of ZnO nanorods increased, while the density of the nanorods decreased. Initial value of the current density increased with a decrease of the Si resistivity, accelerating nucleation and formation of a ZnO nanorods. The saturated current density was increased with a higher Si wafer resistivity, which may be due to an increased surface area of the ZnO layer exposed to the solution, elevating the surface concentration of electrons. (C) 2009 Elsevier B.V. All rights reserved.