A consistent set of ab initio-based kinetic and thermodynamic data is applied for the simulation of an ethane steam cracking furnace. The thermodynamic data are calculated using accurate quantum chemical CBS-QB3 calculations including corrections for hindered internal rotation. The kinetics are obtained from CBS-QB3-based group additive models. With these thermodynamic and kinetic data, simulations for pilot and industrial ethane steam cracking reactors over a wide range of process conditions are performed. It is shown that, without adjusting any parameter, the main product yields can be predicted within 15% rel. of the experimentally observed cracking yields. This indicates the tremendous potential of integrating ab initio methods with engineering models for accurate reactor simulations. © 2010 American Institute of Chemical Engineers AIChE J, 2011