This paper describes corrosion studies in simulated acid rain environments carried out on AISI 316L and 17-4PH stainless steel specimens prepared by powder injection moulding. Corrosion characterization was carried out using a cyclic salt spray test to accelerate the effects of corrosion caused by acid rain. This consisted of wetting and drying cycles using a solution of composition typical of acid rain found in a polluted urban atmosphere. The solution used was concentrated to accelerate corrosion. The results were compared to results from literature for salt spray testing (ASTM B117). In addition, polarization tests and electrochemical impedance spectroscopy (EIS) measurements were performed in the same solution used in the cyclic salt spray test. The results showed that AISI 316L and 17-4PH steels produced by PIM technology are very resistant to corrosion in acid rain environments. Inspection of the surfaces of these steels revealed no corrosion products after 2600 hours of cyclic testing in simulated acid rain solution. Polarization and EIS results in the same solution, indicated a passive state and no pitting tendency of both steels in the test environment.