Catalytic reactor

The invention concerns a catalytic reactor for the catalytic reaction of exhaust gases, in particular for exhaust gases from internal combustion engines. The reactor comprises a honeycombed member (2) which is disposed in a metal casing (1) and comprises a plurality of ducts (3) through which exhaust gas can flow. The honeycombed member (2) further has a gas inlet side (4) and a gas outlet side (5) and, at least over part of its longitudinal extension, is thermally insulated with respect to the inner surface (6) of the casing (1) by internal insulation (8) from the gas inlet side (4) and preferably also from the gas outlet side. The outer surface (7) of the casing (1) also has thermal insulation (9) at least in sub-areas and the casing (1) acts as a heat store at least in sub-areas. This construction gives rise to favourable properties for both cold and hot starting since one sub-area heats up rapidly during cold starting and another sub-area cools only slowly after relatively long operation as a result of heat being stored in the casing.