Bus passengers can now swipe their debit, credit or charge cards directly onto the yellow Oyster readers on all of London's buses.
They will be charged the same amount as the Oyster single fare of £1.35, rather than the cash price of £2.30.
American Express, MasterCard and Visa Europe contactless payment cards will be accepted, but there is no daily price cap on the amount charged, as there currently is with Oyster cards.
Mayor of London, Boris Johnson, said:
“Lots of us have had the frustrating experience of dashing to board a bus only to discover that our Oyster card has run out of credit. So the arrival of this latest technology is welcome news, meaning that with a simple touch of a contactless payment card, people can avoid having to scrabble for change and also still benefit from the Oyster fare discount. This is the latest in a range of ways we are working to make passenger journeys even easier and more convenient.”