Hundreds of thousands of dollars is expected to be raised for charity from the auction of items lost at Sydney Airport over the past 12 months.

From 42 million visitors to the airport in that time, 1,200 items will be sold on Wednesday and Thursday in an online auction.

They include dozens of laptop computers, cameras, jewellery and souvenirs.

More exotic items include guitars, a trumpet and an American oak wine barrel.

"There is a big-screen TV, and bicycle. [It] raises the question how do you lose something like that," Pickles Auctions spokesman Richard White said.

Sorry tourists, they're probably yours

This trumpet was discovered at Sydney Airport and will be sold off in the auction. ( ABC News: David Spicer )

Sydney Airport said overseas tourists were the biggest losers.

"One of the most common places to lose items is through security … when people leave things in the security tray," airport spokeswoman Laura Stevens said.

"Sometimes people aren't sure where they have left items. Maybe they have been travelling in a taxi or a train or through the airport on an airline."

The strangest item ever left at the airport was a wooden leg.

Lost and found twice

This jewellery found at Sydney Airport is packaged up for auction. ( ABC News: David Spicer )

This year one item — a bottle of perfume — was found at the airport with an auction sticker from a previous year.

"Believe it or not this has been lost twice," Mr White said.

The reserve on all items is $1.

Last year the auction raised more than $200,000.