A novel compound, p-(dimethylamino)benzamido-thiosemicarbazide (1), based on intramolecular charge transfer fluorescence was synthesized. In pH 7.4 Tris-HCl buffer, the emission intensity of 1 increased upon the addition of HSA or BSA due to the energy transfer from the protein to 1 and also the hydrophobic microenvironment provided by HSA or BSA. The binding constants between 1 and proteins were 1.41 x 10(5) mol(-1) L for HSA and 8.68 x 10(4) mol(-1) L for BSA, respectively. There is only one binding site. The interaction between 1 and proteins was further investigated by synchronous fluorescence. (c) 2006 Elsevier B.V. All rights reserved.