An approach for the modeling of solid-liquid equilibrium for systems with immiscible solid phases and peritectic reactions is presented in this communication. The method is based on the fact that the liquidus line of solid-liquid equilibrium diagrams correspond to the onset of the solid phase formation, and can thus be calculated through a stability analysis. The method was applied to different systems containing inorganic or organic compounds, yielding results that are similar to those obtained by assigning ad hoc models for activity coefficients of compounds in solid phase. (C) 2012 Elsevier B.V. All rights reserved.