Single-walled carbon nanotubes covalently functionalized with porphyrins present enhanced optical limiting effects. Both porphyrins and SWNTs are good candidates for optical limitin applications. The porphyrin-covalently functionalized SWNTs offer superior performance to C-60, the individual SWNTs, and porphyrins because of a combined nonlinear mechanism and photoinduced electron or energy trans fer between the porphyrin moiety and the SWNTs.