Different Nd3+-doped TiO2 nanoparticles incorporated with heteropoly phosphotungstic acid (HPA) (Nd3+-TiO2-HPA nanocomposites) were synthesized, and their structure and optical properties were characterized. UV-vis diffuse reflectance spectra of Nd3+-TiO2-HPA nanocomposites supported that the nanocomposites absorb visible light as well as ultra violet light. Consequently they exhibit efficient photocatalytic degradation of methylene blue (MB) upon illumination by the solar simulator, and the photocatalytic efficiency was found to depend on neodymium doping and heteropoly acid incorporation. These new photocatalysts were applied to the complete degradation of the organochlorine toxic chemical, 4-chlorophenol (4-CP) in water within 60 min upon sunlight illumination, indicating that Nd3+-TiO2-HPA nanocomposites would be very useful for cleaning polluted surface water by sunlight through the advanced oxidation process. Photocatalytic degradation pathway of 4-chlorophenol was examined using mass spectral analysis. (C) 2015 Elsevier B.V. All rights reserved.