BCR is a modular structured computer program for the simulation of bubble column reactors. It offers very comprehensive options for process engineering calculations for steady-state bubble columns with or without internal installations under various operation modes by determining the local pressure, temperature and concentration profiles over the column height. With the implemented computational methods, new equipment can be analyzed and optimized or the operation range of existing bubble column reactors can be checked and in some cases extended. Potential users are research and development departments in the chemical industry and universities, or research institutes with activities in the field of multiphase reaction engineering. In this contribution, the main program features are described and a short overview is given regarding the calculation methods for fluid dynamic parameters, mass- and heat-transfer coefficients and reaction kinetics in the bubble column, and about methods for considering internal installations such as sieve trays or tube bundle heat exchangers. Some examples are given showing axial temperature and concentration distributions for a bubble column reactor (D = 2 m, H = 20 m) designed for the wet air oxidation of a sewage sludge suspension.