The thermal behavior of gadolinium hydrox-ychloride (Gd-2(OH)(5)Cl center dot nH(2)O, LGdH) has been closely studied to provide the important factors that should be considered for its high temperature applications. Combined analyses of thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DSC-MS) showed that, under atmospheric air with a considerable amount of water, the decomposition of LGdH to Gd2O3 is completed at 1050 degrees C. However, in either dry air or Ar gas, the transformation continued up to around 1300 degrees C. Thus, the thermal decomposition of LGdH was more influenced by H2O than by O-2. FT-IR spectra and X-ray diffraction (XRD) patterns were used to study LGdHs calcined at high temperatures (up to at least 600 degrees C). Calcined LGdH's ability to intercalate anions into the interlayer space could be recovered by the reconstruction of intralayer structure through rehydration and rehydroxylation. These processes were significantly accelerated at elevated temperatures. The recovery behavior of LGdH was examined in different anionic solutions at different temperatures.