Boeing has received an order from Southwest Airlines to begin delivery of 25 737-700 jets at the beginning of 2011.
The airline will use the new 737 aircraft to replace its older classic models of the same plane, which are less fuel-efficient.
Boeing will deliver the 737 jets, each costing between $58.5m and $69.5m, to 2016 under the contract.
The US airline said it has the right to buy 98 planes up to 2021.