Airbus's test crew took the A350-900 prototype to a maximum speed of 340kt during its maiden flight, the equivalent of M0.8, during its cruise test at 25,000ft.
Head of development flight tests Patrick Du Che, one of the six crew members of MSN1, said the achievements during the 4h first flight were "impressive".
He says the crew was able to pressurise the aircraft, retract the landing-gear, and open the flight envelope in all high-lift configurations, from minimum to maximum speed.
Du Che says the aircraft also cruised in clean configuration at 25,000ft and reached 340kt.
Over the course of the next test flight, he says, the crew will explore higher Mach numbers, adding that the aircraft is in a "good state" to continue the campaign.
Chief test pilot Peter Chandler, who commanded the aircraft, says: "The biggest compliment I can give [is] that, after the first few minutes, it didn't feel like we were doing a first flight.
"It felt like we were flying an aeroplane at end of a test programme, not the beginning of a test programme - it was so relaxed and so predictable."
His co-pilot, Guy Magrin, says he was "happy to check the models are matching, very well, the real aircraft".
MSN1 is powered by two Rolls-Royce Trent XWB engines, and flight-test engineer Emanuele Costanzo says: "These engines are excellent, really excellent.
"It's not a surprise. We've had today the confirmation of what we've seen in the last two years since the start of the flying [A380] testbed."
Airbus has released images of the pilots' preparations in the cockpit of MSN1 which also show a data sheet giving further technical details of the first flight.
It indicates the aircraft was carrying just over 50t of fuel - including 20t in each wing tank and 10t in the centre tank - with a ramp weight of 221.5t and a zero-fuel weight of 171.3t. It also lists the take-off speed as 142kt.
Airbus's formal airport planning data for the A350-900 gives the aircraft's maximum zero-fuel weight as 192t and maximum take-off weight at 268t.