Abstract: A honeycomb structure as a substrate for a catalyst has at least one partially melted surface on an outer surface of the structure. A roughness of the melted surface is coarser than other surfaces. With the coarse surface, shifting of the honeycomb structure in through-aperture directions and rotation about its axis are prevented, thereby enhancing the reliability of a catalyst converter incorporating the honeycomb structure therein. A method of producing the honeycomb structure includes steps of, after extruding a ceramic batch into a honeycomb structure, drying the extruded honeycomb structure, attaching a chemical compound having a low melting point at a predetermined position onto an outer wall surface of the dried honeycomb structure, and firing the structure to melt at least a part of the outer wall surface, thereby obtaining the honeycomb structure having a melted portion whose roughness is coarser than the other surfaces of the outer wall.

Abstract: A ceramic honeycomb structural body having a plurality of through-holes surrounded by partition walls wherein, the partition wall thickness in at least a central portion of the structural body at a section perpendicular to the through-hole is thinned stepwise from a crossing segment of the partition wall up to a middle segment thereof.

Abstract: A ceramic honeycomb body has a plurality of through holes defined by partition walls so as to be separated from each other, and fins are integrally formed with selected partition walls so as to extend into the through holes surrounded by such selected partition walls, whereby the cross-sectional area of the through hole is selectively reduced by the fins thus provided.