Abstract: A portable self-heating device includes a heating cell having a fluid permeable wall defining an interior space of the cell. The device includes an outer cover having a fluid permeable section, and an absorbent layer positioned external to the interior space of the cell. The heating cell and absorbent layer are positioned within a cavity formed by the outer cover such that the absorbent layer contacts the heating cell. A user can activate the portable self-heating device by contacting the device with a fluid (e.g., a gas or a liquid) that reacts exothermically with a fluid activated material located in the interior space of the cell. This raises the temperature of the device. This increase can be sufficient to heat any portion of a liquid adjacent or contacting the device such that the liquid is converted to gas and passes out of the outer cover through the fluid permeable section.