Natural gas is a mixture of hydrocarbons with combustible methane as the main component, the content of which usually exceeds 90%. Among the remaining components of natural gas are ethane, propane, butane, nitrogen, carbon dioxide and sulfur compounds. Helium can be also found in some natural gas fields. The composition of natural gas depends on, e.g. the field from which the gas comes, and also way in which it is transported, i.e. pipelines, LNG technology. The quality of natural gas is regulated by respective standards. Gas transmission pipelines are the most popular and dominant method of gas transport on the international gas market, though LNG technology has recently started to play an increasingly prominent role. The intensive development of renewable energy sources is accompanied by the development of the Power to gas technology - the electric energy excess is used for the hydrogen production, which can be directed to the existing natural gas network and such a mixture of natural gas and nitrogen is transmitted. At present, transmission pipelines for nitride natural gas Ls and Lw exist in Poland. The aim of this paper is to analyze the influence of natural gas admixtures on the operational parameters of transmission pipelines.