A computational fluid dynamics (CFD) model of steam methane reforming process over a pre-heated Ni-based catalyst is developed via ANSYS Fluent for real computational domain of the reformer. The investigations are focused on determination of temperature and mole fraction of individual element distribution in the reformer at various initial conditions. The fluid dynamics of reacting flow is studied in experimental setup. It is established that the increasing of the gas flow rate leads to pressure loss increasing. For example, at velocity inlet of 1 m/s the pressure drop is 512 Pa for the investigated reformer. The results of CFD simulation are revealed that the mole fractions of each elements are constantly changing due to chemical reactions when the reaction mixture passes through catalyst bed of the steam methane reformer. When the synthesis gas composition obtained with the CFD model versus the equilibrium syngas composition is compares, it is presented that at the catalyst temperature above 1300 K a syngas composition is close to equilibrium. The distribution of the gas temperature in the reformer is determined by the developed model. The temperature gradient near the reformer inlet has a maximum value, because the temperature drop between catalyst and reaction mixture is maximum and maximum rate of steam methane reforming reaction takes place in this section of the reformer. The temperature gradient slows down to outlet of reformer, because the catalyst temperature decreases due to endothermic steam methane reforming reaction, and also due to increase of steam-to-methane ratio form inlet to outlet due to methane consumption (for inlet steam-to-methane ratio above unit). For follow initial conditions (steam-to-methane ratio is 2.0, pressure is 5 bar, residence time is 4.54 kgcat·s/molCH4, temperature of feed stock is 800 K, catalyst temperature is 1300 K), temperature of outlet synthesis gas is 849 K.