A heat diffuser for use with an electrically-operated aerosol-generating device is configured to be removably coupled to the aerosol-generating device. The heat diffuser includes a non-combustible porous body for absorbing heat from an electric heating element. The porous body is thermally conductive such that, in use, air drawn through the porous body is heated by the heat absorbed by the porous body. Example embodiments also provide a heated aerosol-generating article and an aerosol-generating system, both comprising the heat diffuser.