Abstract We present the growth and characterization of TiO 2 nanocrystals. Nanostructured growth is obtained in a low‐pressure CVD system by using an organometallic precursor Ti(OC 3 H 7 ) 4 as both the Ti and O source catalyzed by both ferrocene (an organometallic precursor) and cobalt metallic clusters prepared by the microwave‐assisted polyol method. Two kinds of TiO 2 structures were obtained in the cobalt clusters: a) pine‐tree like (with short‐leaf structure) and b) long‐leaf structures as large as a few micrometers in size and both under 10 nm in thickness. Long‐leaf TiO 2 structures were grown at cobalt grain boundaries. For the growth conditions utilized, the TiO 2 structures are composed of both anatase and rutile crystallographic phases. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)