An isoperibol solution-reaction calorimeter suitable for measuring molar enthalpies of solid-liquid and liquid-liquid interactions was constructed. The volume of calorimetric vessel made by transparent hard glass is about 100 cm(3). Its energy equivalent is 0.48 kJ(.)K(-1) when containing 100 cm3 of double distilled water. The thermal leakage modulus is 2.7 x 10(-4) s(-1). The time constant of the calorimeter is about 2.9 s. The precision of controlling and measuring the temperature is within +/-0.001 K and +/-0.0001 K, respectively. The performance of the calorimeter was tested by measuring the enthalpy of dissolution of KCl in double distilled water, Delta(s)H(m,KCl)(0) = (17 547 +/- 13 J(.)mol(-1)) at T = (298.15 +/- 0.001) K, and the measuring uncertainty was estimated to be within 0.30% by comparing our measured value with the reference. Molar enthalpies of dissolution of the {ZnCl2(s) + L-His(s)} mixture and the complex Zn(His)-Cl-2(.1)/2H2O(s) in 100 cm(3) of 2 mol(.)L(-1) HCl at T = (298.15 +/- 0.001) K have been measured to be Delta(d)H(m,1)(0) = (26.419 +/- 0.019) kJ(.)mol(-1) and Delta(d)H(m,2)(0) = (11.862 +/- 0.009) kJ(.)mol(-1), respectively, by means of the isoperibol solution-reaction calorimeter. The standard molar enthalpy of formation of the complex Zn(His)Cl-2(.1)/2H2O(s) has been derived to be Delta(f)H(m)(0) [Zn(His)Cl-2(.1)/2H2O, s, 298.15 K] = - (1010.1 +/- 2.3) kJ(.)mol(-1) by the combination of the experimental values of enthalpies of dissolution with some auxiliary thermodynamic data through a designed Hess thermochemical cycle on the basis of a supposed chemical reaction.