Revolut, the digital bank, has launched a UK pilot of a facial-recognition checkout called Pay with Smile.
Customers who sign up can pay by looking at a scanner, rather than using a card or phone.
The service comes bundled with Revolut Register, the company's two-screen point-of-sale terminal.
Revolut is waiving processing fees for merchants during the trial to encourage take-up.
Customers opt in through the Revolut app.
The terminal then matches their face against the selfie taken when they opened their account.
Revolut says merchants do not store customer data, and the company encrypts the payment process.
Analysts are not yet convinced that shoppers need it.
"Biometric payments can offer further convenience to customers, but they have had many false starts," said Zil Bareisis of Celent, the financial research firm.
He warned that the convenience case remains unproven.
Industry advisers say the model depends on persuading merchants to install special hardware.
It also needs to build a network across many retailers, because biometric systems and terminals from different providers do not yet work with each other.
The pilot extends Revolut's existing selfie-based identity checks from its app into physical shops.
It comes as the company tries to grow its merchant services while dealing with recent operational and data-security pressures.
Revolut says it has no current timetable for a wider rollout.
