In this work we present a theoretical investigation of hydrogenated Si(111) surface functionalization by means of propyl-urea molecules. The molecules are found to attach at the silicon surface following an exothermic reaction when the coverage is half of a monolayer. Among the possible SAM configuration, we have found that the most favorable is the one maximizing H-bond interaction between the organic monomers. (C) 2012 Elsevier B. V. All rights reserved.