The decomposition of trichloroethylene (TCE) and Cl sorption by alkaline sorbent were investigated in a reactor filled with CaO or Na2CO3 fine particles. Under a TCE-N-2 atmosphere without CaO and Na2CO3, it was found that HCl, C2Cl4 and CCl4 were generated by the thermal decomposition of TCE at temperatures above 873 K. Similarly, under the TCE-H2O-N-2 atmosphere without CaO and Na2CO3, HCl was generated at temperatures above 673 K, and the presence of CaO or Na2CO3 sorbent was found to promote the decomposition of TCE in the temperature range of 473-1073 K. Under the TCE-N-2 atmosphere in the presence of CaO and Na2CO3 sorbents, HCl and C2Cl2 were generated by the decomposition of TCE; and under the TCE-H2O-N-2 atmosphere, TCE was decomposed to HCl and C2H2Cl2. During TCE decomposition, the formation of CaCl2 and NaCl was observed, and hence it was concluded that Cl gaseous compounds formed by the decomposition of TCE were absorbed on CaO and Na2CO3. As for the Cl sorption on alkaline sorbents, the highest conversion values of CaO to CaCl2 of 0.60 and Na2CO3 to NaCl of 0.53 were obtained at a temperature of 873 K under the TCE-N-2 atmosphere. Under the TCE-H2O-N-2 atmosphere, the conversion of CaO to CaCl2 was higher than that without H2O in the temperature range of 473-873 K. However, at a temperature of 1073 K, the conversion of CaO to CaCl2 decreased. On the other hand, conversion of Na2CO3 to NaCl was higher in the temperature range of 473-1073 K in the presence of H2O than under the TCE-N-2 atmosphere. Under the TCE-H2O-N-2 atmosphere, the highest conversion values of CaO to CaCl2 of 0.72 and Na2CO3 to NaCl of 0.66 were obtained at a temperature of 873 K.