Nitrogen-doped TiO2 nanoparticle photocatalysts were synthesized by a sol-gel procedure using tetra-n-butyl orthotitanate as a titanium precursor and urea as a nitrogen source. Systematic studies for the preparation parameters and their impact on the material's structure were carried out by multiple techniques: thermogravimetric and differential scanning calorimetric analysis, X-ray diffraction, scanning electron microscope, transmission electron microscopy, energy dispersive x-ray spectroscopy and UV-Vis diffuse reflectance spectrophotometry showed that the nitrogen-doped TiO2 calcined at 500°C for 3 h exhibited a spherical form with a particle size about 15-20 nm and crystal phase presented a mixture of 89.12 percent anatase. The obtained product was deposited on a porous quartz tube (D = 74 mm
l = 418 mm) to manufacture an air photocatalytic cleaner as a prototype of the TIOKRAFf company's equipment. The created air cleaner was able to remove 60 percent of 10 ppm acetone within 390 min and degrade 98.5 percent of bacteria (total aerobic bacteria and fungi, 300 cfu m-3) within 120 min in a 10 m3 box. These photodegradation activities of N-TiO2 are higher than that of the commercial nano- TiO2 (Skyspring Inc., USA, particle size of 5-10 nm).