Over the past few decades, titanium dioxide has been an important material for different sectors of modern technology. More precisely, this ceramic has been synthesized in the form of nanomaterial and applied in buildings, dye-sensitized solar cells, hydrogen production, sensors, rechargeable batteries, electrocatalysis, self-cleaning, environmental pollution, and antibacterial actions based on its enhanced optical properties. This book describes preparation, photocatalytic properties, and applications of nanostructured titanium dioxide with a particular focus on non-traditional syntheses and brookite. Titanium oxide nanoparticles are produced by hydrothermal processes, ionic liquid-assisted reactions, biological approaches, ball-milling techniques, etc. Physical properties and potential future applications of the produced nanostructured titanium dioxide nanoparticles are reviewed. Toxicity of titanium oxide nanoparticles and titanium oxide nanowires are also discussed.