Abstract: The hydrogen-induced cracking (HIC) behavior of X70 pipeline steel was studied by means of Linear Polarization Resistance (LPR), hydrogen permeation tests, weight loss and Scanning Electron Microscopy (SEM). In this study, the dissolved H2S was created by chemical reactions in solution. The specimens were immersed into synthetic sea water saturated with H2S. The experimental results showed that the increase of exposure time and H2S concentration leads to an increase of the hydrogen content in X70 steel, which plays a key role in the initiation and propagation of HIC.