Using atomic layer deposition (ALD), RuO2 was deposited on mesoporous Al2O3 with a mean pore size of similar to 12 nm and particle diameter of similar to 1 mm. The entire internal structure of mesoporous Al2O3 was coated by RuO2 nanostructures using ALD, forming a mesoporous bead of RuO2/Al2O3. Substantially high CO oxidation activity at reaction temperatures below 100 degrees C is also shown. There was a decrease in CO oxidation activity with time at 100 degrees C, and post-annealing at 700 degrees C fully recovered the catalytic activity of fresh RuO2/Al2O3. The RuO2/Al2O3 can be useful as an oxidation catalyst for eliminating harmful molecules. (C) 2016 Elsevier B.V. All rights reserved.