The present study numerically investigates two-dimensional laminar force convection heat transfer past two rotating circular cylinders in a side-by-side arrangement at a various range of absolute rotational speeds (vertical bar alpha vertical bar <= 2) for four different gap spacings (g*) of 3. 1.5, 0.7 and 0.2 at Reynolds number of 100, and a fixed Prandtl numbers of 0.7 (air). As vertical bar alpha vertical bar increases, the thermal field became stabilized and eventually steady beyond the critical rotational speed depending on the gap spacing. In general, as vertical bar alpha vertical bar increases, because the vertical motion of flow in the region of gap is strongly inhibited, the inner isotherms are early merged and shorter than the outer isotherms in the free-stream sides elongating further downstream. As vertical bar alpha vertical bar increases, because the rotating fluid near the cylinders surrounded much space where the steady conduction mode is predominant to the heat transfer, the behavior of the time- and surface-averaged Nusselt number has the decaying pattern with increasing vertical bar alpha vertical bar for all gap spacings considered in this study. (C) 2010 Elsevier Ltd. All rights reserved.