The present work deals with conjugated heat transfer in heat spreaders made of a nanocomposite substrate with longitudinally molded multiple straight micro-channels. An experimental analysis is undertaken to validate a recently proposed methodology for the solution of conjugated conduction-convection heat transfer problems, which are often of relevance in thermal micro-systems analysis, based on a single domain formulation and solution of the resulting problem through integral transforms. The single domain formulation simultaneously models the heat transfer phenomena at both the fluid streams and the channels walls by making use of coefficients represented as space variable functions with abrupt transitions occurring at the fluid-wall interfaces. The Generalized Integral Transform Technique (GITT) is then employed in the hybrid numerical-analytical solution of the resulting convection-diffusion problem with variable coefficients. The experimental investigation involves the determination of the surface temperature distribution over the heat spreader with the molded microchannels that exchange heat with the base plate by flowing hot water at a prescribed mass flow rate. The infrared thermography technique is employed to investigate the response of the heat spreader surface temperature to a hot inlet fluid flow, aiming at the analysis of micro-systems that provide a thermal response from either their normal operation or due to a promoted stimulus for characterization purposes. (C) 2014 Elsevier Ltd. All rights reserved.