A honeycomb body having a porous ceramic honeycomb structure with a first end, a second end, and a plurality of walls having wall surfaces defining a plurality of inner channels. A porous material is disposed on one or more of the wall surfaces of the honeycomb body. A method for forming a honeycomb body includes depositing a porous inorganic material on a ceramic honeycomb body and binding the porous inorganic material to the ceramic honeycomb body to form the porous layer.

A honeycomb filter includes: a honeycomb substrate having porous partition walls disposed so as to surround cells extending from an inflow end face to an outflow end face, an outer peripheral coating layer disposed so as to surround an outer periphery of the honeycomb substrate, and plugging portions that are disposed at any one of ends on the inflow end face and ends on the outflow end face, of the cells, wherein, the outer peripheral coating layer has an inflection point at which thermal expansion in thermal expansion behavior of the outer peripheral coating layer turns to contraction and a temperature T1 of which is 1000 to 1500 C., and the outer peripheral coating layer has a porosity P1 of 36 to 48%, and a thermal expansion coefficient C1 between 40 to 800 C. of 2.5 to 3.510.sup.6/ C.

A pillar-shaped honeycomb structure filter including a plurality of first cells and a plurality of second cells, the first cells and the second cells being alternately arranged adjacent to each other with a porous partition wall interposed therebetween, wherein a ceramic porous film, in which an average film thickness T (unit: m) is 2 to 50 m, a porosity P (unit: %) is 65 to 90%, and the average film thickness T and the porosity P satisfy a relational expression of 0.36 T+60P0.75 T+72, is formed on a surface of each of the first cells.