The thermal degradations of chlorinated natural rubbers from latex (CNR-L) and from solution (CNR-S) under nitrogen atmosphere were studied with thermogravimetric analysis (TGA). The thermal degradations of CNR-L and CNR-S are one-step reaction. The shapes of the thermogravimetric and derivative thermogravimetric curves are similar. The degradation temperatures of CNR-L and CNRS increase linearly with the increment of heating rates. The heating rate hardly affects the thermal degradation rates of CNR-L and CNR-S at the various degradation stages. The thermal degradations of CNR-S and CNR-L are dehydrochlonation reactions. The reaction activation energy (E) of CNR, at the first stage, is around 100 kJ/mol. After that, E remains relatively steady (80-140 kJ/mol). At the last stage, E rises rapidly (130-270 kJ/mol). The variation tendency of frequency factor (A) is similar to that of E. As the initial degradation temperature To of CNR-L is 10.9'C lower than that of CNR-S, the thermal stability of CNR-S is better than that of CNR-L, which may be caused by the difference of molecular structure between CNR-L and CNR-S, as FTIR results indicate that there are more -OH, -C=O and -COOgroups in the CNR-L molecular chains. (c) 2007 Wiley Periodicals, Inc.