In this study, the adsorption and catalytic oxidation of asphaltenes, problematic heavy hydrocarbons present in heavy oil, onto two aluminas with different particle sizes and comparable surface acidity were investigated. Equilibrium batch adsorption experiments were conducted at 25 degrees C with solutions of asphaltenes in toluene at concentrations ranging from 100 to 3000 mg/L. Adsorption data were fit to the Langmuir and Freundlich isotherm models. Nano-alumina fit better to the Langmuir model, while micro-alumina fit well to the Freundlich model. On a surface area basis, nano-alumina has higher adsorption capacity for asphaltenes than micro-alumina. Interestingly, micro-alumina has higher catalytic activity toward asphaltene oxidation than nano-alumina, at the same asphaltene loading, thus exhibiting the significance of textural properties during catalytic oxidation of asphaltenes that dominated over the effect of the particle size.