AES, LEED, low resolution ELS and work function measurements were conducted at room temperature on the interaction of CO with Al(111). Three main stages in the adsorption process were observed. Dissociative adsorption led to the incorporation of oxygen and carbon with the formation of amorphous oxidized and carburized aluminium. The initial state of the sample surface strongly determines the adsorption kinetics. In this framework we discuss the effect of structural defects and chemical impurities.