Two methods of finding the Massieu–Planck potential for multicomponent thermodynamic systems are proposed. The first one allows to find the Massieu–Planck potential of the entire system under condition that the Massieu–Planck potential of components are known. In the second case, we suggest a linear partial differential equation that is equivalent to the chemical equilibrium of the system, that also allows finding the Massieu–Planck potential of the system if the Massieu– Planck potential of a subsystem is known