Modeling and scaling assume significance in micro scale combustion due to limited availability of experimental data for the design of microcombustors. In this study, mathematical modeling and detailed computations of an annular microcombustor were employed to obtain scaling laws. Constant inlet velocity and residence time scaling were used for four geometrically similar configurations in the 0.42-1 mm range, covering the quenching limit of stoichiometric hydrogen-air flames. Based on the scaling arguments and a mathematical model, Graetz number emerged as a possible correlating parameter and enabled the formulation of a general correlation between Graetz number and thermal efficiency that could be useful as a scaling law in design process. Computations involving a wide range of operating parameters, equivalence ratio: 0.5-1.7, inlet Reynolds number: 127-1379, and inlet temperature: 300-600 K, were included in the analysis. The procedure developed in this work could also be used to lend credence to the findings of this study and extend the results to other geometries of microcombustors. (C) 2016 Elsevier B.V. All rights reserved.