A joint US-Australian military research team is running a series of 10 trials at the world's largest land testing range, Woomera in South Australia, and at Norway's Andoya Rocket Range.
"It is a game-changing technology... And could revolutionise global air travel, providing cost-effective access to space," Australia's chief scientist Alex Zelinsky said in a statement.
Scientists have said hypersonic technology could cut travelling time from Sydney to London to as little as two hours for the 17,000-kilometre (19,540-mile) flight.
Scientists involved in the programme - called Hypersonic International Flight Research Experimentation (HIFiRE) - are developing an engine that can fly at Mach 7, Michael Smart of the University of Queensland told AFP.
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"It's an exciting time... We want to be able to fly with a hypersonic engine at Mach 7," said Smart, a hypersonics expert involved in the programme which also includes US aerospace giant Boeing and German space agency DLR.
He added that the scramjet was a supersonic combustion engine that uses oxygen from the atmosphere for fuel, making it lighter and faster than fuel-carrying rockets.
The experimental rocket in the trial on Wednesday reached an altitude of 278 kilometres and a target speed of Mach 7.5, Australia's defence department said.
Each test builds on previous ones, with the latest used to measure heat on the outside of a vehicle in hypersonic flight, Smart said.
The next test, scheduled for 2017, would involve the scramjet engine separating from the rocket booster and flying on its own, he added.