Nanostructural (3 0 1) and (10 1) twins of RuO2 Were grown on top of rutile phase TiO2 nanorods (NRs) sitting on LiNbO3(1 0 0) substrate. The surface morphology, structural and spectroscopic properties of the as-deposited nanocrystals (NCs) were characterized by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), micro-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and selected-area electron diffractometry (SAED). The FESEM images and XRD patterns indicated growth of V-shaped RuO2 (3 0 1) and (1 0 1) twins with angles of 51 degrees and 110 degrees between two arms, respectively. The Raman spectrum showed the nanosize induced redshift and peak broadening of the RuO2 and rutile phase of TiO2 signatures with respect to that of the bulk counterparts. XPS spectra indicated the existence of higher oxidation states of ruthenium in RuO2 NCs. TEM and SAED characterizations of the V-shaped RuO2 NCs showed that the nanorods were crystalline RuO2 with twin planes of(3 0 1)/(1 0 1)and twin directions of [(1) over bar 03]/[(1) over bar 01] at the V-junction. The probable formation mechanisms of the twins are discussed. (C) 2009 Elsevier B.V. All rights reserved.