Prototype monolith catalysts with high intrinsic conductivity, consisting of extruded copper honeycombs washcoated with Pd/gammaAl(2)O(3) and suitable for industrial applications (similar to25 mm diameter) in multitubular externally cooled fixed-bed reactors, have been prepared and tested in both pure heat transfer and reactive experiments, using CO oxidation as a strongly exothermal model reaction. Measured temperature distributions indicated radial isothermal operation of the catalysts under the most severe conditions investigated. The limiting heat transfer resistance was located at the interface between the monolith and the reactor tube, and was significantly reduced by appropriate packaging methods controlling the clearance between the monolith and the tube. A detailed analysis, based on a ID heterogeneous non-adiabatic model of the monolithic reactor, provided estimates of the monolith-wall heat transfer coefficient in the range 400-500 W/(m(2)K), which is regarded as very promising for industrial implementation. (C) 2004 Elsevier Ltd. All rights reserved.