This paper investigated the hydration and formation of the AH(3) phase in three structural modifications of ye'elimite (namely, ss-ye'elimite, Sr-ye'elimite, and Ba-ye'elimite). Three structural modifications of ye'elimite were synthesized, and their reactions with water were studied. The similarities and differences of the microstructure of the final AH(3) phase formed during the hydration of different structural modifications of ye'elimite were investigated using a multitechnique approach. The crystal structure of three structural modifications of ye'elimite had an important influence on the kinetics of the reaction. The AH(3) phases formed from ss- and Sr-ye'elimite pastes were nanocrystalline, whereas the AH(3) phases formed in Ba-ye'elimite pastes were microcrystalline. The distinct microstructures of the AH(3) phase in three structural modifications of ye'elimite had been investigated by the amount, composition, and crystal size of the AH(3) phase.