The equilibrium solubility of the ternary system cadmium chloride + DL-alanine (Ala) + water was determined at 298.15 K, and the corresponding equilibrium diagram was constructed. The ternary system is complicated with three equilibrium solid phases, CdCl2 center dot 2.5H(2)O, Cd-3(Ala)(2)Cl-6 center dot 4H(2)O, and Ala, of which a new compound of Cd-3(Ala)(2)Cl-6 center dot 4H(2)O was found to be congruently soluble in the system. The new compound obtained was identified and characterized by the methods of IR, elementary analysis, X-ray diffraction, X-ray diffraction single crystal structure analysis, thermogravimetry, and differential thermogravimetry. It belongs to the monoclinic system, with space group P2(1)/n, a = 0.70393(16) nm, b = 0.9074(2) nm, c = 1.6982(4) nm, beta = 92.529(4)degrees, V = 1.0837(4) nm(3), Dc = 2.434 g.cm(-3), Z = 2. The dissolution enthalpies of Ala, CdCl2, and Cd3(Ala)(2)Cl-6 center dot 4H(2)O in 2 mol.dm(-3) H2SO4 were measured by heat conduction microcalorimetry. By designing a thermochemical cycle according to Hess' Law and through calculation, we obtained the reaction enthalpy of Ala with cadmium chloride, Delta H-r(m)circle minus(298.15 K) = -(50.86 +/- 0.77) kJ.mol(-1), and the standard molar enthalpy of formation of Cd-3(Ala)(2)Cl-6 center dot 4H(2)O, Delta H-r(m)circle minus = -(3499.9 +/- 1.1) kJ.mol(-1).