Synthesis of undoped and Zn doped hausmannite Mn3O4 nanorods was achieved through a simple hydrothermal route. Scanning electron microscopic studies showed that due to in situ Zn doping a structural deformation from Mn3O4 nanorods to a mixture of Mn3O4 nanorods and nanoparticles occurred. The amount of nanoparticles in the mixture increased with the increase of doping percentage. X-ray diffraction studies, transmission electron microscopy and selected area electron diffraction pattern revealed that both the nanorods and the nanoparticles were hausmannite Mn3O4. X-ray photoelectron spectroscopic studies confirmed successful zinc doping in Mn3O4. Microscopic studies revealed that the average diameters of Mn3O4 nanorods and nanoparticles were of 200 nm and 70 nm, respectively. The possible growth mechanism and the reasons behind the formation of nanoparticles along with nanorods are discussed briefly. UV-vis spectroscopic studies showed a continuous increase in the energy bandgap of Mn3O4 with the increase in Zn doping percentage. (C) 2011 Elsevier Ltd. All rights reserved.