The influence of iron oxide (Fe2O3) on the formation and decomposition kinetics of calcium sulfoaluminate (C(4)A(3)$) formed from tricalcium aluminate and calcium sulfate was investigated by both isothermal and isoconversional methods. Rietveld quantitative analysis was used to determine the mineral compositions. The results showed that the addition of 1 wt% iron oxide accelerated both the formation and decomposition of C(4)A(3)$ at a given temperature. The formation and decomposition activation energies obtained by the isothermal method using the Jander diffusion model were 184 +/- 25 kJ/mol and 523 +/- 17 kJ/mol, respectively. The isoconversional methods yielded formation and decomposition activation energies of 191 kJ/mol and 509 kJ/mol, respectively. The isoconversional results were thus in agreement with the isothermal results. This confirmed the validity of the diffusion model, which revealed that both reactions were diffusion mechanisms. With 1 wt% iron oxide, the optimal region for the formation of C4A3$ was found to be in the temperature range 1150-1300 degrees C for sintering times of 8 h to 1 h.