Thomas Cook Group has firmed up a memorandum of understanding with Airbus for 12 A321s.
The UK holiday company signed the MoU last month as part of a five-year plan to replace its narrowbody fleet.
Deliveries of the aircraft, which will be equipped with Airbus sharklets, are scheduled to begin in 2014.
In addition to the 12 A321s, Thomas Cook plans to lease A320-family aircraft from lessors.