We report the growth and characterization of coexistence of vertically aligned and twinned V-shaped RuO 2 nanorods (NRs). The well-aligned RuO 2 NRs were grown on top of rutile (R) phase TiO 2 NRs sitting on sapphire (SA) (1 0 0) substrate via metal-organic chemical vapor deposition (MOCVD) by using bis(ethylcyclopentadienyl) ruthenium (II) and titanium-tetraisopropoxide (TTIP, Ti[OCH(CH 3) 2] 4) as source reagents. 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, transmission electron microscopy (TEM) and selected-area electron diffractometry (SAED). The FESEM images and XRD patterns indicated growth of vertically aligned RuO 2(0 0 1) and V-shaped RuO 2(1 0 1) NRs on top of R-TiO 2 NRs. The Raman spectrum indicated the formation of high quality RuO 2 NCs on rutile phase of TiO 2 NRs. TEM and SAED characterizations of V-shaped RuO 2 NRs showed that the nanorods were crystalline RuO 2 with a twin plane of (1 0 1) and twin direction of [ 1 ¯ 0 1 ] at the V-junction. The probable mechanisms for the formation of well-aligned RuO 2 NRs are discussed.