Since the discovery of the first petroleum off-shore fields 30 meters below sea level in the Brazilian northeastern coast in 1968, the development of new technology for oil extraction and production in deep and ultra deep water has led to the achievement of oil extraction in increasing deepness until outstanding levels such as 1800 meters have been attained in 1999-2000. The necessity of development of new materials to withstand very aggressive work conditions in such deep water with high contents of salts and biogenic generation of H2S led to the search for new alloys with good strength and fatigue properties to resist to the stress generated by wave and tidal motion and vortex induced vibration, beside high corrosion resistance. In the present work, a study is carried out, which simulates the conditions of operation and exploration of petroleum in marine environment for evaluating corrosion resistance and mechanical properties of duplex and 12% chromium stainless steels. The following tests were performed: determination of uniform corrosion rate, local corrosion resistance, stress corrosion cracking resistance in four points bending tests and cyclic slow strain rate tests, in aggressive environments such as aqueous salt solutions with NaCl, H2S and CO2. In addition, tensile and hardness tests were performed as well as microstructural and automatic image analysis. Results show that duplex and superduplex stainless steels were approved in all types of test conditions and presented the best combination of mechanical properties, whereas 12% Cr steel failed in some conditions. Besides, a careful research about new developments on duplex stainless steels was compiled, showing advantages and disadvantages of this kind of material in comparison to other alloys. A searching of recent patents in several data bases show that, among the corrosion resistant alloys, the duplex stainless steels are some of the most promising alloys for oil exploration. However, considerable efforts are being directed towards the development of supermartensitic steels, which with improved properties, can be a lower cost option for such application.