The corrosion behavior of W-Cu alloys, pure Cu and W at different pH was investigated using electrochemical measurements and immersion test. The corrosion behavior and the preferentially attacked phase of the W-Cu alloys changed with pH values as micro-galvanic effect between Cu binder and W phase played a significant role. The micro-galvanic effect was negligible at pH 1 but enhanced as the pH increased from 7 to 13 (Cu and W were cathode and anode respectively). The micro-galvanic effect can be observed from the electrochemical tests, but the actual influence involving kinetics can be observed realistically from the immersion test.