The nanoparticles of a copper phthalocyanine-fullerence dyad were prepared and the optical limiting properties of the nanoparticle dispersion were investigated. The nanoparticle sample (nanoparticle aqueous dispersion) exhibits an enhanced optical limiting performance as compared to the monomer sample (molecularly dispersed solution Of CuPC-C-60/THF). A mechanism based on the formation of ordered aggregates in the nanoparticles, which is expected to exert effect on the electronic structure of the system, is proposed for the nonlinear absorption enhancement of the nanoparticles. (c) 2005 Elsevier B.V. All rights reserved.