Heathrow Express travellers will be able to use US dollars and Euros for purchasing tickets on the service from October 23.
The rail operator said the new multi-currency purchasing service means passengers will now avoid foreign exchange charges, which are typically between 2 and 5 per cent on credit cards.
The facility was introduced exclusively to Avios members this week – Passengers who have signed up to the loyalty points provider can collect Avios on each journey taken on the Heathrow Express.
Multi-currency purchasing will be available across the Heathrow Express website, mobile sites and trade partner sites.
Fraser Brown, commercial director, said: "This is an important step in our strategy to reach an international marketplace. By offering our products in US dollars and Euros we are moving from a UK-centric approach to an international one."
Last week, Flybe announced a partnership with Avios, replacing the regional airline’s existing Rewards4All frequent flyer programme.