The corrosion performance of two types of weldable mattensitic stainless steel seamless pipe for pipeline application is investigated. 11Cr steel pipe developed for sweet environment gives better resistance to CO2 corrosion than the 13Cr martensitic stainless steel for OCTG. 12Cr steel pipe developed for light sour environment shows good SSC resistance in a mild sour environment and superior CO2 corrosion resistance at high temperature and high CO2 partial pressure condition. The suitable condition for the 11Cr steel pipe and the 12 Cr steel pipe in sweet environment, and the critical pH and H2S partial pressure for the 12 Cr steel pipe welded joint in sour environment are clarified. Both welded joints have superior resistance to hydrogen embrittlement under the cathodic protection condition in sea water. Keywords: martensitic stainless steel, CO2 corrosion, sulfide stress cracking, pitting, heat affected zone, cathodic protection, hydrogen embrittlement