57Fe Mössbauer measurements were performed on FeSO3 being in frozen solution and in crystalline states. The obtained typical Mössbauer parameters for crystalline FeSO3.3H2O are IS=1.23±0.05 mm s–1 and QS=2.50±0.01 mm s–1, while for the fozen solution: IS=1.32±0.01 mm s–1, QS=3.24±0.01 mm s–1. It show that FeII is hexaaquacoordinated in the solution.