Alternative energy sources to the traditional fossil fuels have to be explored and understood. One potential energy source being researched and developed is hydrogen gas which could be economically transported through steel pipelines. The degradation of the mechanical properties of steels in hydrogen service is known to depend on the microstructure of the steel. Understanding the levels of mechanical property degradation of a given microstructure when exposed to hydrogen gas under pressure can be used to evaluate the suitability of the existing pipeline infrastructure for hydrogen service and guide alloy and microstructure design for new hydrogen pipeline infrastructure. Microstructures and fracture toughness performances will be compared along with recommendations for future work related to gaining a better understanding of steel pipeline performance in hydrogen service.