The pipelines buried underground are always influenced by sulfate-reducing bacteria (SRB) and cathodic protection (CP). The literature had recorded the fracture accidents of buried pipeline caused by SRB and cathodic potential. To investigate whether SRB can influence the hydrogen damage of pipeline steel under cathodic potential, the synergistic effect of SRB and cathodic potential on hydrogen permeation behavior of X80 steel was investigated by electrochemical tests and optical observation, by which both the growth cycle of microorganism and the applied potential are considered. The results showed that the hydrogen permeation current density of X80 steel in SRB-inoculated solution was three times higher than that without SRB. Serious hydrogen blistering on the surface of specimen was observed in the presence of SRB. The permeation current increases with the negative shifting of the applied cathodic potential in SRB-inoculated solution, which is attributed to the cathodic polarization and the metabolic activities of SRB. The research indicated that the hydrogen damage of pipeline is more likely occurred in the environments with SRB under a more negative cathodic CP potential. (C) 2017 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.