A resource and time saving method is introduced for optimizing fixed bed reactors by the combination of response surface methodology (RSM) and CFD simulation. This is demonstrated for the oxidative coupling of methane (OCM) based on the reaction kinetics by Stansch et al. (1997). Firstly, a parameter screening is performed to identify the power factors modified reaction time, heating temperature and CH4 to O-2 ratio. Secondly, utilizing Central Composite Design, meta models for the most interesting responses are developed, i.e. C-2 selectivity and yield as well as CH4 conversion. The statistical models describe the characteristics of the responses over a wide range. Thirdly, an optimization of C2 yield is carried out using RSM. The maximum is detected to be approx. 14% and validated by three dimensional CFD simulations. In the investigated parameter space the optimized parameter conditions are found for a feed composition of 20% nitrogen, 26.7% oxygen, 53.3% methane (CH4 to O-2 ratio of 2), a modified reaction time of 61 kg s/m(3) and a heating temperature of 801.5 degrees C. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.