Multiwalled carbon nanotubes (MWCNTs) were covalently functionalized with fourth-generation poly(amido amine) (PAMAM) dendrimers with a trimesyl core (DT4), and the as-synthesized MWCNT-DT4 was used as the template for in situ growth of Ag and Cu2O nanoparticles on MWCNTs. Extensive characterizations of the resultant hybrids have been performed using X-ray diffraction, transmission electron microscopy (TEM), high resolution TEM, energy dispersive X-ray spectroscopy, selected area electron diffraction, thermal gravimetric analysis, and X-ray photoelectron spectroscopy. The side-wall of the nanotubes was uniformly coated with the nanoparticles with mean sizes of 7-8 nm. The optical limiting property measurements of the nanoparticle-modified MWCNTs were carried out by the open-aperture z-scan technique. The results demonstrate that the samples suspended in water show broadband CL performance, and their CL behavior is better than that of MWCNT-DT4 in water due to the presence of Ag and Cu2O nanoparticles. (C) 2012 Elsevier B.V. All rights reserved.