An atmospheric pressure plasma-enhanced nanoparticle synthesis (APPENS) process was proposed to produce a titania-based visible light photocatalyst. The titanium tetraisopropoxide (TTIP) precursor was vaporized with a N2 carrier gas and entered a nonthermal AC plasma system. The N2 gas was dissociated into N atoms by the plasma energy, and then they were doped into the precursor vapors. The produced TiO2-xNx nanoparticles were highly uniform and adjustable in size. The titania-based particle sizes ranged from 25 to 40 nm, and they depended on the precursor ratio of TTIP/H 2O. In addition to producing the photocatalytic particles, the APPENS process has a potential application as a continuous-flow nanosize monodisperse aerosol generator.