Tris[2-(8-chinolinyloxy)ethyl]amine (L) has been developed as a highly selective fluorescent chemosensor for Cd 2+ based on the chelation-enhanced fluorescence (CHEF) mechanism. Its sensing behavior toward metal ions was investigated by absorption and fluorescence spectroscopy. In buffer solution (10mM Tris–HCl, pH=7.4) of L, the presence of Cd 2+ induces the formation of a metal–ligand (Cd 2+ –L) complex, which exhibits a strong, increasing fluorescent emission centered at 417nm. The binding mode of the Cd 2+ –L complex has been found to be 1:1 based on the fluorescence/absorption titration and further confirmed by X-ray crystallography.