The low-temperature phase equilibria in the In-Pb system are calculated using the CALPHAD approach. The Gibbs energies of the solution phases in the In-Pb system are modeled thermodynamically using the Redlich-Kister expression. Model parameters are determined by considering both the thermodynamic data and the phase boundary data in the literature. The calculated phase diagram and thermodynamic properties agree well with those determined experimentally. The model is then used to extrapolate the low-temperature behavior of the In-Pb system. The calculation predicts that the alpha+(Pb) two-phase field will widen as the temperature is lowered. The model also predicts a eutectoid reaction: alpha=(In)+(Pb) at -64 degrees C. This suggests that, at very low temperature (<-60 degrees C), most of the In-Fb alloys would exist in the form of two-phase.