The mathematical description of complex chemical kinetics is very common in the field of combustion science. These days we have methods to describe and solve chemical systems containing hundreds of chemical species and reactions. The production processes of fine chemicals or other typical products of chemical industry often involve the same elementary reaction steps as used for the modeling of combustion phenomena. The application of this knowledge base in chemical engineering science is not widely adopted. The detailed modeling of elementary reaction steps could help to reduce byproducts, increase operating stability and reduce the time needed for plant revisions. This work gives an outline ol the methods and tools needed to model complex chemical systems. As an example, results from numerical calculations of the thermal decomposition of tetrachloromethane in methane are compared with experimental data.