The results from mathematical modeling of a block of reactors of a high-temperature hydrocarbon pyrolysis line are presented. Models of tube furnaces for homogeneous pyrolysis with variously designed coils are described as ideal-displacement reactors. Application of a determinative approach to the reaction mechanism and determination of the kinetic parameters for thermal decomposition of hydrocarbons and their use for describing the processes occurring in SRT-1 and SRT-2 pyrolysis furnaces showed agreement between the calculated relationships and the experimental data.