Abstract: The heating device for heating liquid and solid products comprises a heating element intended to heat a food preserve (314) or container structure. The heating element consists of a flat tile like element including a heat spreading layer (308) made of heat conducting material, an intermediate layer (303) composed by an exothermic gas-less combustible material and a layer of heat insulating incombustible material (301). The intermediate layer contains internal walls (302) defining a fire path in order to control the duration of the exothermic reaction. Ignition means comprises a cup-shaped primer (305) with in its center a protruding cone (307) and a starter (311) consisting of a striker arranged to be drawn across a friction sensitive element and intended to ignite the tip of said cone (307) of the primer (306), which in its turn induces the reaction to the combustible material (303).