In chemical growth of 1-D ZnO nanorods the selection of hydroxide anion generating agent plays a crucial role in determining the growth rate and morphological features. Due to misconception regarding the role of hexamethylenetetramine (HMTA) in the growth of ZnO nanorods, it is heavily used as hydroxide anion generating agent for ZnO nanorod growth. Though it needs repetitive renovation of growth solution and longer time deposition for the growth of high aspect ratio ZnO nanorods. Here we have carried out a comparative study on the effect of hydroxide anion generating agents (HMTA and ammonia) on growth, morphological, structural, chemical, optical, and photo-electrochemical properties of ZnO nanorods, in view to assist in the selection of the these agents in ZnO nanorod growth. (C) 2014 Elsevier Ltd. All rights reserved.