A novel carboxyamide ligand has been synthesized using maleic anhydride and ethylenediamine. Co(II), Ni(II), Cu(II) and Pd(II) complexes of the ligand, i.e., N,N’-bis(3-carboxy-1-oxo-z-prop-2-elenyl)ethylenediamine [H2L] have been prepared and characterized by elemental analyses, IR, electronic, 1H NMR, EPR spectral and thermal studies. It is revealed by IR and 1H NMR spectral studies that the ligand coordinated to the metal ions through deprotonated carboxylate oxygen and non-deprotonated amide nitrogen in all the complexes. It is suggested by electronic spectral and magnetic moment studies that N2O2 coordination is around each metal center with a strong field square planar chromophore. All the complexes have been studied by TGA and DTA studies done simultaneously. The complex formation between ligand and metal ions [Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)] has also been studied pH metrically in 75% aqueous DMF solution at 298 K in 0.1 M NaClO4. The probable structures of the complexes have also been proposed.