Passive films of specimens having bulk chemistry that simulate the post irradiated grain boundary chemistry of type 304 stainless steel (S.S) were studied in-situ using contact electric resistance (CER) method in a static autoclave containing high temperature pure water. For comparison, conventional stainless steels also were tested. The results show that the passive films of the materials having simulated chemistry were of 'n' type semiconductors as in the case of conventional S.S. High phosphorus containing material showed higher electric resistance of passive film at all the test conditions whereas, high Si containing material showed passive film instability at high temperature, which could be associated with the dissolution of silicates. Moreover, the CER data associated with the instability in the passive film of high Si material could be correlated with the observed higher crack growth rate in PWR primary water environment. There is a possible correlation between the observed electric resistance data of the passive film of type 316 S.S and the published data on SSRT of type 316. In addition, CER measurements were carried out on Ni-Cr alloys with different Cr contents. Ni base alloys with 8-16% Cr content showed 'n' type behavior of passive film. Alloy 690 type material showed 'p' type passive film. Higher electric resistance of passive films of 8% Cr and 16% Cr samples could be correlated with the observed SCC susceptibility during SSRT.