A new microreactor design featuring embedded passive mixing elements was tested as a means to enhance autothermal reforming reaction of biogas over a novel Re-Ni/gamma-Al2O3 catalyst. To determine an optimal condition that would result in completely converted biogas with H-2/CO product ratio of around one and minimal hot spot formation inside the reactor, use of various inlet O-2 and H2O concentrations and inlet temperatures were numerically investigated. The influence of inlet reactant velocity on the reactor effectiveness was then studied at the optimal condition. Performance of a straight-channel microreactor was also studied and compared with that of the novel microreactor. The O-2:H2O:CO2:CH4 ratio of 25:5:28:42% (v/v) and inlet temperature of 730 degrees C were noted as the optimal condition for the novel microreactor. Complete biogas conversion over a wider range of inlet Reynolds number, lower required catalyst loading to achieve the desired reactor performance, higher H-2 and CO selectivities and reduced hot spot formation were noted as the advantages of the novel microreactor. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.