The occurrence, in a nuclear reactor, of the reaction chain:6Li(n,t)4He;32S(t,n)34mCl has been experimentally established. Experimentation for its application to the activation analysis determination of lithium has been carried out, and a radiochemical method for separation of34mCl is presented. The sensitivity is 0.4 g for the following conditions; 15 min irradiation (thermal flux: 1.5·1013 n·cm–2·s–1); 30 min decay; 2,000 s measurement (semiconductor detector).