In the present work, a simple and cost effective successive ionic layer absorption and reaction (SILAR) method was adopted for the first time to grow well oriented crystalline ZnO seed layer films. The highly oriented ZnO hexagonal micro/nanorods were grown over seeded glass and Si (1 0 0) substrates by a simple chemical bath deposition (CBD) process at various pH. The surface morphology studies found that the diameters and orientation of the ZnO micro/nanorods has been tailored by varying the pH of the solution. The SEM analysis reveals that the ZnO rods were grown vertically with perfect wurtzite hexagonal shape and their diameter ranges from 300 nm to 1 mu m at optimized pH concentration. The XRD patterns of both ZnO seed layer and micro/nanorods grown films exhibit highly crystalline orientation of ZnO wurtzite structure with a (0 0 2) plane orientation, preferentially. The Raman spectra provide evidence for the presence of defects and oxygen vacancies in these nanostructures, which are responsible for the photoluminescence (PL) in the visible region. Biodegradability study on ZnO rods confirms the etching and dissolving behavior of rods over a time period which could act as the Zn ions nutrition. This simple and integrated approach, could lead to a cost effective and convenient way to large scale growth of ZnO rods with subsequent huge interest in future nano-based biosensor applications. (C) 2012 Published by Elsevier B. V.