This paper describes the Kenyalang-1 ("Hornbill-1") unmanned aircraft system (UAS) which was developed as an alternative energy technology demonstrator. The propulsion system is powered either purely by a proton exchange membrane (PEM) fuel cell or alternatively by a hybrid power system of the fuel cell augmented with a two-cell lithium polymer battery. the fuel cell is capable of providing 500 W of continuous power, fed by gaseous hydrogen stored in a pressurized, composite tank. It is the first of its kind entirely designed, built, and test flown in Southeast Asia. Details of the aircraft system and flight tests are presented.