Temperature-controlling solid-liquid phase change material (PCM) infiltrated in a porous matrix is becoming attractive for aerospace applications. The properties of the pore structure are crucial factors in the selection of porous materials for PCM infiltration. The main purpose of this study is to adjust the pore structure of porous silica matrices with different molar ratios of ethanol (EtOH) and tetraethoxysilane (TEOS) for PCM infiltration. Five compositional ratios of EtOH/TEOS were introduced to prepare the silica with different pore size through sol-gel processing, and the pore structures were analyzed by N-2 adsorption-desorption measurements and scanning electron microscopy. Results indicate that the pore size increases with a larger value of the EtOH/TEOS molar ratio. Open cell pore structure and pore size of silica were observed and calculated. For EtOH/TEOS ratios of 10 and 20, the synthesized silica matrices had average pore sizes of 53.1nm and 56.0 nm, respectively, exhibiting better infiltration. Moreover, the maximum mass fraction of paraffin as PCM in the silica matrices reached up to 75 wt%. Crown Copyright (C) 2010 Published by Elsevier B.V. on behalf of The Institution of Chemical Engineers. All rights reserved.