Display omitted •Cryptomelane-type manganese oxides were prepared by a solvent-free method.•Ceramic and metallic monoliths were washcoated with cryptomelane.•High catalytic activity of the structured materials was observed.•Thermal conductivity was the key factor to understand the results.•The different supports did not significantly change the activity of the catalyst. Ceramic and metallic monoliths coated with cryptomelane-type manganese oxides were prepared and tested as catalysts for the oxidation of ethyl acetate. Several preparation conditions were optimized in order to enhance the activity of the monoliths. Monoliths with different cell sizes, prepared with the same number of immersions in the washcoating solution or with similar loadings were tested in order to evaluate the effect of this parameter on the adherence of the active phase and on the catalytic activity of the final monolith. Several characterization techniques were used to assess the properties of these monoliths and it was found that almost all properties of the active phase were maintained after the washcoating process. The thermal conductivity of the structured supports must be taken into account in order to interpret the catalytic results in highly endothermic or highly exothermic reactions. The location of the measurement thermocouple is decisive when analyzing the results since it can give rise to apparent differences in activity. In our specific case, the available data suggest that the specific activity of the catalyst is not significantly altered by the deposition process or by the properties of the supports used.