Pretreatment temperature affects the activity of a RhRe/C catalyst for C-O hydrogenolysis of 2-(hydroxymethyl)tetrahydropyran and for dehydration of fructose. Catalytic activities for both C-O hydrogenolysis and dehydration were observed to decrease with an increase in pretreatment temperature from 393 to 723 K, which coincides with a decrease in the number of sites quantified using NH3 temperature-programmed desorption. Results for the characterization of RhRe/C using X-ray absorption spectroscopy (XAS) are consistent with the formation of Rh-rich particles with a shell of metallic Re islands after reduction at 393 K, which shows penetration of Re into the nanoparticie with increasing reduction temperature. No evidence of rhenium oxide was found from the Re L-III-edge MS spectra after reduction at temperatures above 363 K or under aqueous operando conditions. The apparent acidity of FthRe/C is suggested to be generated from the activation of water molecules over Re atoms on the surface of metallic Rh Re particles. (C) 2013 Elsevier Inc. All rights reserved.