The molar heat capacity and the standard (p 0 = 0.1 MPa) molar enthalpies of formation of the crystalline of bis(glycinate)lead(II), Pb(gly)2; bis(dl-alaninate)lead(II), Pb(dl-ala)2; bis(dl-valinate)lead(II), Pb(dl-val)2; bis(dl-valinate)cadmium(II), Cd(dl-val)2 and bis(dl-valinate)zinc(II), Zn(dl-val)2, were determined, at T = 298.15 K, by differential scanning calorimetry, and high precision solution-reaction calorimetry, respectively. The standard molar enthalpies of formation of the complexes in the gaseous state, the mean molar metal–ligand dissociation enthalpies, M(II)–amino acid, $$ \langle D_{\text{m}} \rangle $$ (M–L), were derived and compared with analogous copper(II)–ligand and nickel(II)–ligand.θθ M(II)–amino acid $$ \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} $$ (cr)/kJ mol−1 Bis(glycinate)lead(II), Pb(gly)2 −998.9 ± 1.9 Bis(dl-alaninate)lead(II), Pb(ala)2 −1048.7 ± 1.8 Bis(dl-valinate)lead(II), Pb(val)2 −1166.3 ± 2.5 Bis(dl-valinate)cadmium(II), Cd(val)2 −1243.7 ± 2.7 Bis(dl-valinate)zinc(II), Zn(val)2 −1306.1 ± 2.3