The aim of this work is to numerically investigate the ignition behavior of homogeneous-heterogeneous (HH) combustion of propane in a Pt-catalyzed microburner to delineate the role of homogeneous chemistry during cold-start ignition. A two dimensional model with one-step homogeneous and catalytic mechanisms in a parallel-plate microburner is considered. The ignition characteristics (ignition temperature and ignition time) are explored for catalytic microreactor with and without homogeneous chemistry. We show that the catalytic reaction lights-off first, followed by the homogeneous reaction. Consequently, the homogeneous chemistry does not affect the ignition behavior of the catalytic microburner. The effect of inlet velocity, wall thermal conductivity and gap size on ignition characteristics is explored. The ignition characteristics are not affected by homogeneous chemistry even at larger gap sizes, despite the fact that the homogeneous contribution at steady state increases with increasing gap size of the microburner.