Nitrogen (N)-doped titanium dioxide (TiO2) particles of nanometric size are directly synthesized in an atmospheric microwave plasma-torch using gas-phase titanium tetrachloride (TiCl4). The absorption edge of the TiO2-xNx powders shifts from 365 to 500 nm in UV-visible spectrum, as the content x of nitrogen in titanium dioxide powders increases from x = zero. From the results of the XRD, XPS, and UV-visible data, incorporation of N into the O site of TiO2 was enhanced in a mixture of N-2 and O-2 by an atmospheric microwave plasma torch, contributing to the band gap narrowing. (c) 2005 Elsevier B.V. All rights reserved.