We report on the fabrication of UV LEDs based on a p-n junction p-ZnMgO/n-ZnO/n-ZnMgO double heterostructure. Pulsed-laser deposition was used to grow the complete heterostructure on c -plane sapphire templates. The LEDs were patterned by simple wet etching. Band-edge electroluminescence emission most likely associated with ZnO excitonic transitions was observed at room temperature. However, the devices show sensitivity to the presence of hydrogen in the measurement ambient due to formation of a surface conduction layer. The results show the potential of ZnO-based materials for UV emitters of potentially lower cost and with comparable or higher emission intensity than AlGaN/GaN devices provided adequate surface passivation techniques are developed.