For successful application of high-alloyed stainless steels for Flue Gas Desulfurization (FGD) plants, pitting corrosion resistance of arc welds of N-added 6%Mo austenitic stainless steels (UNS N 08367) and super duplex stainless steels (UNS S 32550) made with various filler metals were evaluated using the “Green Death” solution. For Gas Tungsten Arc (GTA) and Gas Metal Arc (GMA) welds of N 08367, Critical Pitting Temperature (CPT) of base metal was 65 -7O°C, whereas weld made by ERNiCrMo-3 filler metal yielded CPT of 50°C. Welds made by ERNiCrMo-10 or ERNiCrMo-4 filler metals showed CPT of 60 -65°C and 65 -7O°C, respectively. For GTA and GMA welds of S 32550, CPT of welds made by ERNiCrMo-3 was 45-5O°C, indicating that the filler metal can provide pitting corrosion resistance matching the S 32550 alloy. Thus, a proper pitting corrosion resistance of weldments of high-alloy stainless steels can be achieved by selecting filler metals having at least +lO higher Pitting Resistance Equivalent Number (PREN) value than the base metal regardless of the type of arc welding process. The over-alloyed filler metals would compensate preferential segregation of Cr, MO along the dendrite boundary, which made the dendrite core more susceptible to pitting. Nitrogen addition to the GTA welds of N 08367 made with ERNiCrMo-3 failed to improve pitting corrosion resistance, which was attributed to the precipitation of nitrogen in the weld metal in the form of Nb-nitride. Keywords: FGD, N-added 6%Mo austenitic stainless steels (UNS N 08367), super duplex stainless steels (UNS S 32550), pitting, GTAW, GMAW, green death solution