Surface-confined dehalogenation reactions are versatile bottom-up approaches for the synthesis of carbon-based nanostructures with predefined chemical properties. However, devices generally requiring low conductivity substrates, potential applications are so far severely hampered by the necessity of a metallic surface to catalyze the reactions. In this work we report the synthesis of ordered arrays of poly-p-phenylene chains on the surface of semiconducting TiO2(110) via a dehalogenative homocoupling of 4,4”-dibromo-terphenyl precursors. The supramolecular phase is clearly distinguished from the polymeric one using Low Energy Electron Diffraction and Scanning Tunneling Microscopy as the substrate temperature used for deposition is varied. X-ray Photoelectron Spectroscopy of C 1s and Br 3d core levels traces the temperature of the onset of dehalogenation to around 475 K. Moreover, Angle-Resolved Photoemission Spectroscopy and Tight Binding calculations identify a highly dispersive band characteristic of a substantial overlap between precursor’s π states along the polymer, considered as the fingerprint of a successful polymerization. Thus, these results establish the first spectroscopic evidence that atomically precise carbon-based nanostructures can readily be synthesized on top of a transition-metal oxides surface, opening the prospect for the bottom-up production of novel molecule-semiconductor devices.