Cancer Research UK has installed contactless payments technology in shop windows, enabling passersby to tap their cards to make donations.
The option will be available at four of the charity's shops - in Brighton, Guildford, Kensington and Marylebone - for a two week period around World Cancer Day on 4 February.
Anyone who taps their contactless card against the window will automatically donate £2 and prompt an interactive screen to show how the money will be used.
Paul Clarke, director of innovation, Cancer Research UK, says: "The contactless giving through four of our shop windows is a new and exciting way for people to donate to our work and help us bring forward the day when all cancers are cured."