Studies were carried out to evaluate the stress corrosion cracking (SCC) behavior of a X-70 microalloyed pipeline steel, with different microstructures by means of the slow strain rate testing (SSRT) technique at 50 ºC. Tests solutions consisted of 0.1, 0.05, 0.01 and 0.005 M sodium bicarbonate (NaHCO3) with KCl, CaCl2 and MgSO4-7H2O additions. Different anodic and cathodic potentials were applied. Additionally, experiments using the SSRT technique but with pre-charged hydrogen samples and potentiodynamic curves at different sweep rates were also done to elucidate hydrogen effects in this type of steel. The results showed that the different microstructures in conjunction with the anodic applied potentials shift the cracking susceptibility of the steels evaluated.