The new cobalt(II) complex of a general formula{Na(H2O)2[Co(bcma)(H2O)]·5H2O}n (bcma3− = 2-methylnitrilotriacetate anion) has been synthesized and structurally characterized. The compound is isostructural with its nitrilotriacetate (nta3−) analogue, {Na(H2O)2[Co(nta)(H2O)]·2H2O}n, and crystalize in the orthorhombic space group Pbca as the Co(II)-Na(I) heterometallic coordination polymer. In the structure of the title compound the zigzag chains formed by {[Co(bcma)(H2O)]−}n anions, combined by Na(H2O)2+ cations, can be found to form two-dimensional frameworks. Furthermore, the coordination properties of bcma3− and nta3− ligands towards the cobalt(II) ions have been investigated in aqueous solutions by using the isothermal titration calorimetry (ITC) technique. The quantification of the metal-buffer interactions and their incorporation into the ITC data analysis enabled to obtain the pH-independent and buffer-independent thermodynamic parameters (K, ΔG, ΔH and ΔS) for the reactions under study.