The spectroscopic characteristics and the crystal structure of Eu(III) complex with picolinic acid N-oxide ligand, picNO, at room and liquid-nitrogen temperatures are discussed. Studies concerning the Eu(III) ion luminescence (intensity, luminescence lifetime measurements, and excitation spectra of the D-5(0) -> F-7(0) transition) are presented. The selective excitation luminescence spectroscopy of Eu(III) in the range of the D-5(0) -> F-7(0) transition is used for the study of Eu/picNO complexes in solution equilibria. In the crystal the complex molecules build the two-dimensional structures with additional Na+ cations and water molecules. This structure consists of edge-sharing chains of Na distorted octahedral, interconnected by Eu polyhedra (distorted square antiprisms). The ligand, pyridine-2-carboxylate-1-oxide, coordinates to the Eu(III) ion as an ionic bidentate chelate, forming the Na[Eu(picNO)(4)] complex of six-membered chelate rings with the bite angles of ca. 70.5 degrees. The complex is symmetrical; the Eu(III) ion is eight-coordinated. (C) 2008 Elsevier B.V. All rights reserved.