A full-scale, 2-D, axially symmetric, heterogeneous, and transient mathematical model is utilized to evaluate the dynamic operation of a honeycomb monolithic reactor during CO2 methanation. A base case is defined, which considers a step-type functionality for H2 load reduction (-20%) and a Ni catalyst. The impacts of the catalyst type (Ni vs Ru), the functionality of the H2 load disturbance, and the monolith's diameter on reactor performance are studied and compared to the base case. Results show that the use of Ru as catalyst, a ramp-type disturbance and a smaller reactor diameter generate a superior dynamic response to the H2 feed disturbance as well as favorable effects on thermal behavior. This is despite the higher temperature gradient generated when using Ru. These findings suggest that the monolithic reactor is a viable technological option for CO2 methanation under flow variations, such as those encountered when employing green hydrogen.