Features of the fully electric trains include USB power slots by the seats, business first class, new work tables, onboard HD TVs and a redesign.
There will be six Class 387 trains, with 48 carriages and 374 seats in total, which were all previously used by Great Western Railway.
They will be stored and maintained by GWR at its Reading depot as part of a partnership with Heathrow Express announced in March 2018.
“Our new fleet of trains will offer the same fast, frequent and reliable Heathrow Express service for years to come,” said Heathrow Express director Les Freer.
The fleet will replace Class 332 trains, which have been in service for 22 years and carried more than 115 million passengers across 44 million miles.
