Optical absorption and photoluminescence (PL) properties of colloidal TiO2 nanombes, produced by the alkali hydrothermal method, were studied at room temperature in the range 300-700 nm. Nanotubes having an internal diameter in the range 2.5-5 nm have very similar optical properties, in contrast to the expected behavior for quasi-1-D systems. This is explained by the complete thermal smearing of all 1-D effects, due to the large effective mass of charge carriers in TiO2, resulting in an apparent 2-D behavior of TiO2 nanombes.