The promotional effect of Cu on the performance of supported Pt catalysts in the selective hydrogenation of ortho- and para-chloronitrobenzene was studied at unprecedented large substrate/Pt molar ratio (20,000) using carbon nanotubes and activated carbon as supports. The catalysts were characterized by N-2 adsorption at -196 degrees C, H-2 chemisorption, TEM, TPR and XPS in order to correlate the corresponding properties with catalytic performance. Strong interactions between Pt and Cu result in partial coverage of the Pt surface by Cu. It is suggested that the superficial Cu species activate the N=O bond of chloronitrobenzene and also inhibit the adsorption of the desired product chloroaniline. Thus, the bimetallic catalysts exhibited excellent performance in producing selectively chloroanilines (>99%), in comparison to monometallic catalysts (91-98%). Moreover, the stability was much improved in comparison to the monometallic catalyst. (C) 2013 Elsevier B.V. All rights reserved.