Prestwick Airport is being put up for sale by the Scottish government.
The airport was taken into public ownership six years ago after it was threatened with closure following heavy losses.
Transport Scotland said an advert would be placed in the Official Journal of the European Union, inviting expressions of interest.
Ministers have regarded Prestwick Airport as a strategic economic asset, particularly for Ayrshire.
It passed into state hands after being bought by the Scottish government for £1 in late 2013.
The Scottish government said then that the deal would help protect the airport and safeguard thousands of direct and indirect jobs.
Prestwick has been looking to turn around it fortunes, including applying to carry out horizontal space launches from its 2,986-metre concrete case runway.
Transport Secretary Michael Matheson said: "Since the Scottish government bought Glasgow Prestwick Airport in 2013, we have been clear that it is our intention to return the business to the private sector when the time is right.
"The senior management team at the airport has continued to engage with potential buyers and investors to discuss proposals for developing the business under new ownership.
"Good progress continues to be made by the airport to increase revenue, deliver operating efficiencies and pursue exciting opportunities for the future, including Spaceport."
The preferred bidder will need to meet four requirements:
- To give a commitment to maintain aviation operations and maximise the employment potential associated with the business
- Have significant investment capabilities
- To be capable of operating and managing an airport
- To have the ability to develop aviation services
Mr Matheson added that any expressions of interest would be "considered carefully" before any decision was taken to divest the government's shareholding in the airport or any part of the business.
The Scottish Conservatives welcomed the decision to sell the airport.
Ayr MSP John Scott said: "Prestwick has all the foundations for success - the longest commercial runway and parallel taxiway in Scotland, a reputation of being Britain's only fog-free airport, its own dedicated railway station, and a thriving aerospace campus.
"What it now needs is an owner prepared to put in the investment to take the airport forward as the major economic asset it undoubtedly is."
Scottish Labour's transport spokesman Colin Smyth said the Scottish government "cannot simply wash its hands of Prestwick".
He added: "They have a responsibility to ensure that if a buyer is actually found, any sale must secure the jobs at Prestwick.
"Anything else would be an economic tsunami for Ayrshire and beyond."
In January, it emerged that the debt owed by Prestwick Airport to the Scottish government had risen from £30m to £38.4m.
That was while revenue rose through a doubling of funds from refuelling aircraft at the publicly-owned facility.
Accounts lodged with Companies House showed the holding company made a loss of £7.6m in the year to March 2018, down from £8.6m the previous year.