Physical and chemical adsorption of methanol and ethanol on the hydroxylated chromium oxide surface was studied. Surface hydroxyls were classified into three groups according to their reactivity with alcohols. Both methanol and ethanol are physisorbed on the first group surface hydroxyls which can be adsorption sites for H2O molecules giving rise to the two-dimensional (2D) condensation. The second ones are active hydroxyls for H2O adsorption and also are reactive with alcohol adsorption to give surface alkoxides. The third one is inactive to both alcohol and H2O adsorptions. Upon heating, chemisorbed alcohols are desorbed at first as molecules by recombination of alkoxyls and hydroxyls. Surface reactions occurred to give the dimethyl ether and ethylene from surface methoxide. Molecular ethanol is desorbed from the surface ethoxide as in the case from surface methoxide. Ejection of ethylene is remarkable after molecular ethanol desorption. Butene and its fragments are observed in a desorbed gas with molecular methanol, indicating that a combination reaction of decomposition products occurs on the chromium oxide surface.