Hydrous amorphous chromium oxide (Cr2O3 . nH(2)O) and crystalline one (Cr2O3) powders prepared by heating Cr(OH)(3) . nH(2)O at different temperatures were separately ground with La2O3 powder using a planetary ball mill at room temperature to investigate mechanochemical synthesis of LaCrO3. Hydrous amorphous chromium oxide prepared reacts with La2O3 to form LaCrO3 and the reaction proceeds with an increase in grinding time. No reaction takes place in the case of crystalline Cr2O3. The ground sample consists of agglomerates and large particles with size up to around 100 mum and shows low specific surface area of about 5 m(2)/g. The mechanochemical method can be also used to synthesize other chromium rare earth complex oxides by grinding the mixture of hydrous chromium oxide and rare earth (Pr, Nd and Sm) oxides.