An improved honeycomb-like monolith with asymmetrical channels, where the channels section decrease along the monolith, was fabricated using a template prepared by 3D printing. A reference honeycomb monolith was also prepared in the same way but with conventional straight channels. Cu/Ceria active phase was loaded on these supports, and SEM-EDX, Raman spectroscopy and XRD showed that the supported active phase is similar on both monoliths. The supported catalysts were tested for CO oxidation in excess oxygen and for preferential CO oxidation in H-2-rich mixtures (CO-PROX), and the catalyst with the improved support achieved higher conversions in both reactions. The supported catalyst with asymmetrical channels has two benefits with regard to the counterpart catalyst with conventional symmetrical channels: improves the reaction rate with regard to the conventional one because fits better to the equation rate, and favors the turbulent regime of gases with regard to the laminar flow that prevails in symmetrical channels.