Well faceted CuO nanoparticles were synthesized by thermal-assisted green strategy at reflux temperature in a short period of time. A possible growth mechanism of such highly faceted nanostructures based on typical biomolecule-crystal interactions in aqueous solution is tentatively proposed. The large surface area (223.36 m(2)/g) and rich exposed active sites are expected to endow such nanostructures with excellent performances in catalysis as demonstrated here for remarkable catalytic activity with respect to the N-arylation of indoles. Nanoparticles were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Both the activity and selectivity of the N-arylation reactions could be tuned by varying the concentration of CuO nanoparticles. Nanoparticles catalyst were recycled and reused for further catalytic reactions with minimal loss in activity. A variety of indole derivatives afforded corresponding N-arylation product with excellent yields (up to 98%). (C) 2012 Elsevier B.V. All rights reserved.