This paper presents numerical and experimental investigations on forced convection in meso-channels with realistic cross-sectional shapes. The numerical study is based on Finite Difference solution of the governing equations, incorporating actual irregular cross-sectional profiles of fabricated channels in the flow domain, using image processing. The numerical results are benchmarked with analytical results. Parametric studies have been performed with channels of different hydraulic mean diameters. Experimental studies have been performed using the optical technique of Mach-Zehnder interferometry to obtain the temperature distributions and calculate heat transfer parameters in water flow through transparent meso-channel. The experimental Nusselt number values were compared and contrasted with numerical predictions using the model developed, for apparent regular geometry as well as the actual irregular geometry. The findings suggest that some of the observed deviations in the performance of small channels, compared to theoretical results, are possibly due to the assumption of regular domain shapes while performing theoretical analysis. (C) 2013 Elsevier Ltd. All rights reserved.