The characterisation of rare earth elements carbonates (REECs) was performed by thermal analysis (TG-DTG) combined with simultaneous infrared evolved gas analysis-Fourier transform infrared (EGA-FTIR) spectroscopy. The TG-DTG curves were obtained using the Perkin-Elmer PC series TGA-7 thermogravimetric analyser in the temperature range 25-800 degreesC both in dynamic air and nitrogen atmosphere.La-2(CO3)(3).nH(2)O, Eu-2(CO3)(3).nH(2)O and Sm-2(CO3)(3).nH(2)O were analysed, the dehydration and decarbonation steps were investigated and the water content was calculated. The trace rare earth elements in lanthanum, europium and samarium carbonates were determined by Philips PU 7000 inductively coupled plasma atomic emission spectrometry (ICP-AES) and the concentration of REE ranged from 6.2 x 10(-5) to 4.2 x 10(-4)% (W/W). (C) 2003 Elsevier Science B.V. All rights reserved.