The study dealt with the effects of different sulfate solutions of sodium, potassium, calcium and magnesium ions on the hydration reactions of tricalcium aluminate (C3A). The hydration was performed at room temperature for different time intervals from half an hour up to 7 days with W/S ratio of 10. The hydration products were investigated by using XRD, FTIR and SEM. The ettringite phase was detected for all systems except in MgSO4 solution. In case of MgSO4 solution, magnesium hydroxide and gypsum were precipitated after half hour; and no ettringite was detected up to 7 days. According to this study, the used alkali metal type influences the hydration product and the rate of hydration for C3A.