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The high alloyed austenitic stainless steels such as Fe-15Cr-25Ni type alloys are used in severe environment where a good combination of corrosion resistance and mechanical properties is required in a wide range of elevated temperatures. The high temperature stability of austenitic stainless steels correlates with microstructure of the steels consisted of (-matrix with stable second phases. The alloying elements incorporated into the alloys modify the second phase precipitation and affect the properties. Recently, it is found that the addition of W and Nb into the Fe-15Cr-25Ni steel improved the mechanical propertires and corrosion resistance of the alloys. In this work subsequence investigation has been conducted to clarify the effect of heat treatment on the pitting resistance of the developed Fe-15Cr-25Ni-2W-2Nb steel. The steels were prepared by induction melting following with hot forging and heat treatment. Both the temperature of solution treatment and of aging were varied and the cyclic polarisation were measured on each samples of difference heat treatment temperature. The observation by SEM was taken on some samples for microstructural confirmation. In general, the solution treated sampel had higher pitting potential than the aged ones. The pitting potential increased with the increasing solution treatment temperature. The SEM images showed the precipitation high Nb containing precipitates.