Cr/SiO2 (MCM-41) materials were prepared by the sol-gel method by hydrolysis of tetraethylortosilicate (TEOS) using cetyltrimethylammonium bromide (CTAB) as a template. The effect of hydrothermal treatment between 120-220 degrees C on the structural properties was studied. Well ordered Cr/MCM-41 with a very narrow pore size distribution was obtained after hydrothermal treatment from RT to 150 degrees C. Materials synthesized at higher temperatures (200 or 220 degrees C) showed the collapse of the ordered mesoestructure to give mesoporous Cr/SiO2 with an open surface. Superficial Cr3+/Cr6+ ratio was determined by XPS over materials hydrothermically synthesized at different temperatures, and calcined in air at 300 degrees C. The hydrothermal treatment improved the chromium to silica interaction, promoting a higher resistance to form Chromium (VI) sites. The chromium (Ill) ions incorporated to the silica structure developed acid sites responsible for the 2-PrOH dehydration. (C) 2013 Elsevier Ltd. All rights reserved.