A combined experimental and numerical study was conducted to understand the effect of rotation of outer cylinder on heat transfer from a vertical heated inner cylinder. The dimensionless analysis carried out for this problem underlines that the non dimensional heat transfer depends on the rotation parameter, radius ratio and aspect ratio. Experiments were conducted for the rotational parameter ranging from 0 ≤ ζ ≤ 526 at different heat loads, keeping the aspect ratio and radius ratio unchanged. Numerical simulations have been performed (for a wide range of rotation parameter 0 ≤ ζ ≤ 526 and fixed radius ratio) using a commercial computational fluid dynamics package ANSYS CFX 14. The heat transfer was found to increase progressively with increasing rotational parameter until a certain value of rotational parameter was reached, thereafter a sharp decay in heat transfer resulting from destabilization of flow field was observed. Three laminar heat convection modes, namely; natural, mixed and forced convection dominant, have been observed during the increasing phase of Nusselt number with rotation parameter. The transport mechanism under different heat transfer regimes was explored and discussed with the aid of numerically simulated flow and thermal fields.