We report on the two-photon-excited (TPE) fluorescence spectrum and lifetime of a new chlorin derivative photosensitizer (CDP) in 0.9% NaCl solution with femtosecond laser pulses at 800 nm. The TPE fluorescence spectrum is similar to that obtained by one-photon excitation (OPE). The lifetimes of TPE and OPE fluorescence of CDP are of the order of 4.7 and 5.0 ns, respectively. The two-photon absorption (TPA) cross-section is sigma(2)' approximate to 33.6 x 10(-50) cm(4) s photon(-1) at 800 nm. Our results indicate that the TPE and OPE photodynamic processes of CDP are basically similar. The lifetime and TPA cross-section suggest CDP may be a potential agent for two photon fluorescent microscopy and imaging as well as a photosensitizer in photodynamic therapy. (C) 2004 Elsevier B.V. All rights reserved.