| Summary: | The gray-colored oxygen-deficient TiO<sub>2–δ</sub>(B) nanobelts have been synthesized through a combination of the hydrothermal method followed by an ion exchange process and vacuum annealing. Electron paramagnetic resonance reveals an existence of <i>F</i>-centers in the form of electron-trapped oxygen vacancies within the anionic sublattice of the gray bronze TiO<sub>2</sub> that induces its colouration. The diffuse reflectance spectroscopy showed that the formation of oxygen vacancies into TiO<sub>2</sub>(B) significantly increases its absorption intensity in both visible and near infrared ranges. The band gap of TiO<sub>2</sub>(B) with anionic defects is equal to 3.03 eV (against 3.24 eV for white TiO<sub>2</sub>(B) treated in air). Room temperature ferromagnetism associated with the defects was detected in gray TiO<sub>2–δ</sub>(B), thus indicating it belongs it to the class of dilute magnetic oxide semiconductors. It was found that in the low-temperature range (4 K), the magnetic properties of vacuum annealed TiO<sub>2</sub>(B) do not differ from those for TiO<sub>2</sub>(B) treated in air. We hope that the findings are defined here make a contribution to further progress in fabrication and manufacturing of defective TiO<sub>2</sub>-based nanomaterials for catalysis, magnetic applications, batteries, etc.
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