A feasible route to produce hydrocarbon termination to the porous silicon (PSi) surface has been introduced using thermal decomposition of acetylene molecules. Treatment temperatures lower than 600 degreesC enable the use of continuous acetylene flushing during the treatment without problems arising from the graphitization of acetylene. The continuous acetylene flushing was found to significantly improve the quality and efficiency of the treatment. The decomposition process starts at low temperatures and appears to consist of three different parts as a function of temperature. It was also found that the treatment time has some effects on the treatment efficiency. The hydrocarbon terminated PSi surface was found to be hydrophobic, when the treatment temperature was below 680 degreesC. Due to the hydrogen desorption, the surface quickly changes to hydrophilic above 700 degreesC. Thermal oxidation studies of the treated surfaces show improvements in the stability against oxidation and the hydrocarbon termination was found to be very stable even in aqueous KOH environment. (C) 2003 Elsevier B.V. All rights reserved.