Isothermal titration calorimetry (ITC) directly provides the detailed thermodynamic characterization (Gibbs free energy ΔG, enthalpy change ΔH, entropy change ΔS, and the stoichiometry n) in solution. Since the release of commercially available ITC in the early 1990’s, the number of studies that have adopted this method has increased. In particular, ITC instruments with small sample volumes have the adequate sensitivity to measure the heat change upon interaction and have accelerated the application of this method in various fields, including biochemistry, medicinal chemistry, structural biology, and material sciences. In this paper, using program SEDPHAT which has attractive features for non-linear fitting of the binding isotherm, as representative cases of SEDPHAT analysis, we describe the ITC data analyses for A+B <-> AB and A+B+B <-> ABB systems and the global fittings.