By means of mathematical modeling the patterns of change the physical and chemical properties, necessary for calculations the gas networks of low pressure, for gas-hydrogen mixtures with volume fraction of hydrogen from zero to 100 % were found. The regularities of gas-dynamic calculations of lowpressure steel gas networks in the case of transportation of gas-hydrogen mixtures with different volume fraction of hydrogen while maintaining the costs and energy consumption of the elements of the gas supply system, typical for the transportation of natural gas were established.