The saccharide containing in high-starch crops could be converted into various products such as 5-hydroxy-methyl-furfural (HMF) which could be used to manufacture plastics. Currently, most of plastics are produced from petroleum feedstock that is one of the main sources of greenhouse gases. Therefore, the use of HMF produced from high-starch crops might reduce the generation of greenhouse gases since the high-starch crops is renewable. For example, D-fructose derived from high-starch crops could be decomposed into HMF in concentrated hydrochloric acid solution. The HMF could be effectively recovered by phenyl groups surface modified silica gel (PMSG) adsorbent during the decomposition process. However, the optimum loading of phenyl groups on the silica gel surface of PMSG would rely on time-consuming experimental works. Therefore, this research focuses on using Molecular Mechanics Simulator based on frontier orbital theory to obtain the optimum loading of phenyl groups on the silica gel in order to reach the maximum adsorption capacity of HMF. The simulated optimum loading of phenyl groups on the silica surface was about 0.5 mequiv./g. This dosage was in consistent with the value obtained from the experimental tests. (c) 2007 Elsevier B.V. All rights reserved.