Two new square planar Cu(II) and Ni(II) complexes, [CuL1(NCO)] (1) and [NiL2(N3)] (2) have been synthesized with two different tridentate N2O donor Schiff base ligands L 1 H (1:1 condensation product of benzoylacetone and 2-diethylaminoethylamine) and L 2 H (1:1 condensation product of benzoylacetone and 2-dimethylaminoethylamine), respectively. Both the complexes 1 and 2 have been characterized by elemental analysis, IR, UV-Vis spectroscopy, room temperature magnetic susceptibility measurement, electrochemical, thermal, and single crystal X-ray diffraction studies. Structural studies reveal that in both the complexes metal centers have square planar environment with N2O donor set of Schiff base ligands and terminal pseudohalide anions (isocyanate for 1 and azide for 2) at four coordination sites of square plane. Square planar complexes of Cu(II) and Ni(II) with N 2 O donor set of two Schiff base ligands: synthesis and structural aspects Subhra Basak, Soma Sen, Samiran Mitra, C. Marschner, W. S. Sheldrick Two new square planar Cu(II) and Ni(II) complexes, [CuL1(NCO)] (1) and [NiL2(N3)] (2) have been synthesized with two different tridentate N2O donor Schiff base ligands L 1 H and L 2 H respectively. Both the complexes 1 and 2 have been characterized by elemental analysis, IR, UV-Vis spectroscopy, room temperature magnetic susceptibility measurement, electrochemical, thermal and single crystal X-ray diffraction studies.