3CaO.3Al(2)O(3).CaSO4 is the main component of the sulpho-aluminate early-strength cements. Its hydration properties decide the strength and long-term stability of the hydrated cement paste. In this article, such hydration properties and the effect of hydration temperature, as well as the addition of NaNO3, on the hydration process are studied. Using the Calvet conducting C80 microcalorimeter, the rate of production of hydration products was determined quantitatively and the total hydration heats calculated. The kinetic parameters for the hydration process at different hydration temperatures and different hydration periods are also calculated. The change of kinetic parameters between those of pure 3CaO.3Al(2)O(3).CaSO4 and those with added NaNO3 are discussed, and are used to explain the anti-freezing properties of NaNO3 on the hydration of cements.