Nanocrystalline LaFeO3 was synthesized by calcining precursor La-2(CO3)(2)(OH)(2)-Fe2O3 center dot 1.5H(2)O in air. XRD analysis showed that precursor dried at 80 degrees C was a mixture containing orthorhombic La-2(CO3)(2)(OH)(2) and amorphous Fe(2)O3 center dot 1.5H(2)O. Orthorhombic LaFeO3 with highly crystallization was obtained when La-2(CO3)(2)(OH)(2)-Fe2O3 center dot 1.5H(2)O was calcined at 900 degrees C in air for 2 h. Magnetic characterization indicated that the calcined product at 900 degrees C behaved weak magnetic behavior at room temperature. The thermal process of La-2(CO3)(2)(OH)(2)-Fe2O3 center dot 1.5H(2)O experienced five steps, which involves, at first, dehydration of 0.8 absorption water, then dehydration of 0.7 crystal water, decomposition of orthorhombic La-2(CO3)(2) (OH)(2) into orthorhombic LaCO3OH, reaction of two LaCO3OH into hexagonal La2O2CO3 and crystallization of tetragonal Fe2O3, at last, reaction of hexagonal La2O2CO3 with tetragonal Fe2O3 into orthorhombic LaFeO3 . In the DTG curve, four DTG peaks indicated the precursor experienced mass loss of four steps. (C) 2012 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.