The current limit on contactless payments using cards, Apple Pay and Google Pay is £30, after which, people need to enter a pin number to authenticate transactions.
The biometric card RBS is developing would mean customers would not need to use a pin code to verify transactions over £30.
The pilot of the bank card involves 200 RBS and Natwest customers in the UK. It is due to start in April and last three months.
The cards are fitted with a built-in sensor, which is powered by payment terminals.
The lender said the technology would improve security and make payments at tills easier.
The UK's largest banks, including RBS, Lloyds Banking Group PLC (LON:LLOY), Barclays PLC (LON:BARC) and HSBC Holdings PLC (LON:HSBA), have been playing catch-up on digital banking as new online rivals take away market share.