The share of renewable energy resources is consistently rising in the global energy supply, and power-to-gas technique is being seen as the feasible storage of surplus renewable electricity. In this regard the sensitivity of hydrogen towards various elements of the P2G network needs to be assessed. The study provides an overview of a number of P2G projects mainly concentrated in Europe, and summarizes the results of investigations carried out on the effects of hydrogen injection on the existing natural gas pipeline infrastructure. It has been found that each element of the natural gas infrastructure has a varying degree of acceptability to hydrogen concentration; however the determinant element affects the overall allowable hydrogen concentration. In the transmission network, compressors are the determinant element and have a limiting value of 10% hydrogen admixture. Distribution network and storage elements allow a 50% concentration of hydrogen. End use appliances have a tolerant range of 20-50%. The second portion of the study demonstrates the effect of hydrogen injection on gas quality, which reveals that an introduction of 2% hydrogen in the distribution network has negligible effect however a 10% hydrogen mixture affects the calorific value of the supplied fuel gas below the desired level. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.