The crystal structure and absorption spectroscopy results of the Na(3)[Nd(TTHA)].2.5NaClO(4).7.617H(2)O compound are presented. The crystal structure of the complex was determined by X-ray analysis. Crystals are monoclinic, space group C2/c, with a = 38.446(8) Å, b = 10.552(2) Å, c = 25.796(5) Å, beta = 130.51(3) degrees, and Z = 4. The structure consists of monomeric (triethylenetetraaminehexaacetato)neodymate anions, perchlorate anions, sodium cations, and water molecules. The Nd(III) ion adopts a 10-coordinate geometry with six oxygen atoms and four nitrogen atoms from a ligand molecule, which is best described as a bicapped square antiprism. Absorption spectra of a single crystal were measured at room and liquid helium temperatures. Intensities of the f-f transitions were analyzed on the basis of Judd-Ofelt theory. The good correspondence between the spectra of [Nd(TTHA)](3)(-) in solution and in the single crystal suggests close similarity of both coordination polyhedra.