Highly crystalline Al(OH)(3) particles were successfully prepared by the sol gel process of aluminum isopropoxide (Al(OPri)(3)) in a hydrophilic ionic liquid (IL), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) at 30 degrees C using NH4OH as catalyst. Moreover, crystalline alumina particles were prepared from the Al(OH)(3) particles by heat treatment at 300 degrees C. When 2-propanol was used as medium for comparison, obtained particles were low crystalline AlO(OH). This difference seemed to arise from the difference in the local structure of Al(OPri)(3) in IL.