Thermoelectric coefficient measurements in the system Fe3O4‐Fe2TiO4 were used to determine the cation distributions from 600° to 1300°C. The cation distributions obeyed the relation ‐RT In K=‐9.61+2(‐0.0154T)b+0.0256T (kJ/mol)where KFecd is the iron distribution constant and b is the tetrahedral Fe3+ concentration. Low‐temperature extrapolations agreed with experimental magnetometry and lattice parameter results. With the incorporation of a subregular size‐mismatch term, agreement with high‐temperature thermodynamic data was achieved. A solvus at intermediate temperatures was correctly predicted by the model.