The goal of this study was to model and optimize the thermal performance of an unglazed transpired solar collector (UTC) prototype using a full factorial experiment with four factors (hole diameter, absorber coating, irradiation and mass flow rate) at three levels. A quadratic polynomial model for efficiency was shown to explain 95.47% of the variance of thermal output. Residuals analysis and analysis of variance were used to validate the best-fit model. Finally, the model was optimized using response surface representations. An optimal combination of levels of the four parameters was obtained to provide a collector efficiency of 70-80%. The chosen experimental methodology provided accurate characterization of the parameters that have the greatest impact on UTC performance. (C) 2012 Elsevier Ltd. All rights reserved.