Seven novel solid complexes of the first-row transitional metal with L-a -histidine were synthesized, and their compositions were determined. The constant-volume combustion energies of the complexes were measured by a precision rotation bomb calorimeter. The standard molar enthalpies of combustion and the standard molar enthalpies of formation were calculated. The results indicated that the plots of the standard enthalpies of formation against the atomic number of the metal show a regularity of zigzag. Seven novel solid complexes of the first-row transitional metal with La -histidine were synthesized, and their compositions were determined. The constant-volume combustion energies of the complexes were measured by a precision rotation bomb calorimeter. The standard molar enthalpies of combustion and the standard results of the plots of the standard enthalpies of formation against the atomic number of the metal show a regularity of zigzag.