The objective of this program was to gain a better understanding of the safety problems of primary LiSOCl
2 and LiSO
2 cells by carrying out detailed thermal modeling work. In particular, the transient heat generation rates during moderate and extremely high discharge rate tests of LiSOCl
2 cells were predicted and compared with those from the electrochemical heating. The difference between the two may be attributed to lithium corrosion and other chemical reactions. The present program was also evaluated in charging tests of LiSO
2 cells. In addition, the present methodology should be applicable, with minor modifications, to analyses of other primary cylindrical cells as well as rechargeable batteries.