Mid-infrared electroluminescence is reported for the first time from InAs0.75Sb0.25 quantum dot (QD) light emitting diodes. The QDs were grown from the liquid phase at 590 degreesC on an InAS(100) substrate and embedded within the undoped active region of an InAs homojunction pin diode. At 4 K and 250 mA injection current, a broad emission band was observed, centred at similar to 4 mum, associated with transitions involving confined holes inside the InAsSb quantum dot. The QD emission band exhibits a blue shift with increasing injection current and the electroluminescence results indicate the presence of a phonon bottleneck in these devices. The QD electroluminescence was observed to persist up to room temperature. (C) 2002 Elsevier Science B.V. All rights reserved.