Thermodynamic analysis of the steam reforming of natural gas at a temperature of 300–600 °C, pressure 0.1–4 MPa and Н2О : С molar ratio 0.8–1.2 was carried out. Under these conditions, the reaction products are methane-hydrogen mixtures with the hydrogen concentration 10–30 vol.%. Raising the temperature and Н2О : С molar ratio as well as decreasing the pressure make it possible to increase the hydrogen concentration in the reaction products. Thermodynamic boundaries of the process in the absence of catalyst coking were determined. Experiments on the formation of methane-hydrogen mixtures from methane with the outlet hydrogen concentration 15–35 vol.% were performed on a commercial Ni-CrOx-Al2O3 catalyst at a temperature of 325–425 °С, Н2О : С molar ratio 0.8–1.0, and atmospheric pressure. Under the indicated conditions, the process was not accompanied by the formation of carbon on the catalyst.