A case for a portable electronic device (especially for an iPhone and the like) comprises a shell 50, an electroluminescent (EL) panel 10 and associated power and control electronics housed on a printed circuit board 20. The electronics on the PCB include a connector 22 for mating with a corresponding connector on the portable electronic device so as to form an electrical connection to a power source in the portable electronic device. Another of the electrical components is There are further provided an inverter 24 and a transformer 26 to convert the low voltage DC power from the portable electronic device into approximately 180 V AC as required to power the EL panel 10. The shell 50 has a clear back 52 through which light produced by the EL panel 10 shines. Interchangeable graphics panels 100 can be slid into a pocket disposed between the EL panel 10 and the back 52 of the shell so as to customise the visual appearance of the case and hence the portable electronic device inside.