Abstract Presented paper summarizes results of slow strain rate (tensile) test in the presence of hydrogen of the carbon steel of type A333 Gr.6 according to ASTM. Steel was tested in as-received state and after quenching and tempering in accordance to the following regime: 870 °C / 40 min / water + 600 °C /2 hours / air. Microstructure of steel in as-received state was ferritic-pearlitic and after heat treatment– quenching and tempering was a mixture of tempered bainite and ferrite. The aim of this work was to demonstrate the influence of hydrogen on the degradation of material with different microstructure by slow strain rate test (tensile), where the strain rate was 10 5 s1. The impact of surface quality to resistance of steels against hydrogen embrittlement was also evaluated. Tensile specimens were divided into two groups. The first groups represented tensile specimens with a standard surface roughness. The second groups represented specimens with finely ground surface to eliminate potentional sites for defect initiation and subsequently to decrease a risk of early failure of specimens. Specimens were submitted to the fractographic analysis of fracture surfaces after tensile test using the stereomicroscope and scanning electron microscope In both cases, in initial state and after heat treatment fracture has a cup character and from the fractographic viewpoint it is transgranular ductile fracture with dimple morphology. More detailed determination of fracture character was obtained by SEM. There is mainly transgranular cleavage fracture, however, there are small areas of quasi cleavage fracture (QCF), reminding so-called “fish eyes”. As well, surface quality improvement of tested specimens didn't lead to increasing of material resistance against hydrogen embrittlement.