The kinetics of simultaneous dehydrogenation of propane and isobutane over a commercial Pt-Sn-K/Al2O3 catalyst is reported. The experiments were carried out in a laboratory-scale plug flow reactor over the temperature range of 560-600 degrees C at atmospheric pressure. Several Langmuir-Hinshelwood mechanisms for C-3 and iC(4) were tested. Models were derived with the assumption of propane, isobutane and hydrogen adsorption on the same type of active site. A simple deactivation model was used for fitting the kinetic data, then the best fit for these reactions was found with the rate determining step (RDS) of surface reaction for propane and adsorption on the catalyst surface for isobutane. The results showed a good agreement between experimental and calculated data for these simultaneous reactions. (c) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.