Computers are used nowadays in many cases in all fields including industrial chemistry. This lecture is limited to special techniques, that can be covered only casually by other courses. A focal point is the theory and application of numerical (mathematical) methods to problems of reaction engineering (numeric integration (Runge-Kutta), linear and non-linear regression). After an introduction into these methods and into the programming language FORTRAN, the participants develop their own programs for the calculation and the regression of kinetics of complex reactions as well as for the calculation and the optimisation of chemical reactors (tube reactor with heat balance, optimisation of a tray reactor for SO3-production). Advanced application of the table calculation program Excel (adaptation of group contributions for the estimation of substance data (solver), visualisation of the course of thermodynamic data in homologous rows (auto filter) will be given. The application of computers in the unit controlling and data acquisition will be discussed during a guided visit of the labs of the department of industrial chemistry.