The effects of pre-irradiation with gamma-rays prior to thermal decomposition on the induction periods of nickel oxalate have been investigated. The results indicated that the induction period of the investigated salt does not appear to be reduced systematically with the gamma-ray dose in the range 10(3) < phi < 10(6) Gy where phi is the gamma-ray dose absorbed by nickel oxalate. The pre-irradiation changed the kinetics of propagation and growth of the decomposition centres in highly irradiated samples attributed to radiation damage of the crystals. Electrical conductivities of gamma-irradiated samples were measured during the thermal decomposition of nickel oxalate and the results were evaluated.