Large area Co3O4 nanotube arrays were fabricated through a metal-organic chemical vapour deposition (MOCVD) template route using the Co(tta)2 · tmeda (Htta = 2 thenoyl-trifluoroacetone, tmeda = N,N,N′,N′-tetramethylethylendiamine) as precursor and anodic aluminum oxide (AAO) as template. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated a very uniform distribution of nanotubes forming an array on a very large scale of the order of mm2. X-ray diffraction (XRD) pattern shows the formation of the Co3O4 cubic spinel phase. The electron diffraction confirmed the crystalline Co3O4 phase even after removal of the AAO template. Spectroscopic ellipsometry was used to measure the optical properties of nanotubes and to discuss the effect of the nanostructure with respect to the optical properties of Co3O4 thin films.