An influence of propane addition to the inlet feed on the performance of industrial fluid bed reactor for isobutane dehydrogenation was experimentally and numerically studied. Experiments on dehydrogenation of propane-isobutane mixture in a pilot fluidized and in a lab fixed bed reactors were performed over Cr2O3/Al2O3 industrial catalyst. Adding C3H8 to the reactor inlet was found to increase experimental conversion of C-3-C-4 mixture and the total process selectivity to olefins. Results of the mathematical modelling of the industrial-scale fluidized bed reactor show some benefits of C3H8 addition. Selectivity to i-C4H8 was found to be high enough and grows slightly from 86 to 89% on increasing inlet C3H8 fraction from 0 to 60 wt%. Inlet concentrations of C3H8 up to 20 wt% lead to the apparent selectivity to C3H6 exceeding 100%. Coke yield rises slowly allowing safe industrial fluid bed reactor operation. (C) 2011 Elsevier B.V. All rights reserved.