An accessory device suitable for use with an electronic device is disclosed and may be designed to provide a protective cover and dissipate heat from the device. Regarding the latter, the accessory device may include a thermally conductive layer disposed in the accessory device. The thermally conductive layer may extend from a first end of the accessory device proximate to a heat-generating component in the electronic device, to a second end away from the heat-generating component. The thermally conductive layer is designed to navigate heat away from the heat-generating component to the second end where the heat escapes the accessory device. The second end may include one or more openings to facilitate heat transfer from the accessory device. In other embodiments, the accessory device includes a phase change material that absorbs heat and changes to a liquid, then passes the heat to another location in the accessory device.