A nanohybrid adduct of the widely used, functional dye, daunomycin (DM), with single-walled carbon nanotubes (SWNTs) was prepared. Ultraviolet-visible-near infrared and fluorescence spectroscopy and electrochemistry of DM-functionalized SWNTs reveal that DM interacts with SWNTs through strong pi-pi stacking and there is a significant photo-induced charge-transfer interaction between the two components. Importantly, the novel adduct modified the glassy carbon (GC) electrode to give a much enhanced electrochemical activity than those of DM adsorbed onto not only the bare GC electrode but also the SWNTs-modified GC electrode.