Hematite particles were obtained by hydrothermal reaction from ferric hydroxide in the presence of citric acid which is acted as crystal growth controller. Citric acid was adsorbed with citrate anion on the ferric hydroxide. Adsorbed citrate anion influenced crystallization temperature and morphology of α-Fe₂O₃in the solid reaction. Adsorbed citrate anion inhibited crystallization of α-Fe₂O₃from ferric hydroxide at pH 9.0-10.5 and induced to needle-like α-Fe₂O₃particles at pH 10.75-11.75 in the hydrothermal reaction.