A heater for treatment of a fluid flow, a method of manufacturing a heater, and method of treating an exhaust gas with a heater. The heater includes a honeycomb structure including an array of intersecting walls defining channels extending axially between a first face and a second face. The intersecting walls comprise a thermally conductive material. A resistive heating element is engaged against the first face of the honeycomb structure. The heating element comprises an electrically conductive element coated with a thermally-conductive electrical insulator. The thermally-conductive insulator electrically insulates the electrically conductive element from the honeycomb structure.