The covalent attachment of a custom functionalized coumarin derivative onto the sidewalls of carbon nanohorns (CNHs) is reported. The new CNH-coumarin hybrid material was fully characterized with complementary spectroscopic, thermal, and microscopy techniques. The photophysical properties of the CNH-coumarin hybrid were explored with the aid of steady-state and time-resolved photoluminescence measurements, in both polar and non polar solvents. Finally, the redox potentials of the hybrid material were evaluated by electrochemistry. (C) 2011 Elsevier B.V. All rights reserved.