Iridium-doped TiO2 having a brookite phase was synthesized as a visible light-active photocatalyst. It was prepared by using a hydrothermal assisted-microwave process as an improved competitive production method over the traditional hydrothermal process. The prepared materials were tested for decomposing acetaldehyde or toluene in gas phase under visible light irradiation lambda 455 nm), and they showed a strong photocatalytic activity response. The activity of the prepared brookite TiO2 material was optimized by adjusting the concentration of iridium ions as a dopant. The photocatalytic efficiencies of all of the prepared Ir-doped-TiO2 photocatalysts were higher than the values obtained from commercially available visible-light responsive photocatalysts under the same experimental conditions. (C) 2014 Elsevier B.V. All rights reserved.