Results are reported on: (i) evaluation and comparison of threshold hydrogen concentration for hydrogen induced cracking (HIC) in linepipe steels; (ii) threshold pH for steels at which no cracking was observed; (iii) observation of cracking by an ultrasonic C-scan technique; and (iv) quantitative characterization of non-metallic inclusion populations in linepipe steels. The results are discussed in terms of cracking sensitivity, HIC susceptibility and effects of non-metallic inclusions in the linepipe steels on HIC. Keywords: HIC, hydrogen sulphide, pipeline, nonmetallic inclusions, materials selection