The localized corrosion resistance of three ferritic stainless steels containing 21% Cr and different amounts of Ca was determined and comparison was made with SS304 as a benchmark. The Ca content had insignificant effect on the resistance to localized corrosion which was found to be similar to that of SS304. The ferritic steels had no MnS inclusions and pits were found to initiate in the matrix next to duplex inclusions that exhibited a higher Volta potential than the matrix.