The fuel cell buses to carry passengers on routes in the Gatwick Airport, Crawley and Horley areas, the start of an order that will create one of the largest hydrogen bus fleets in Britain.
These single-decker GB Kite Hydroliner buses, manufactured by Wrightbus, are the first hydrogen powered vehicles in the operator's fleet of more than 6,000 buses.
A further 34 buses will join the Metroline fleet over the next 18 months through its partnership working with Surrey County Council, which has invested a total of £16.4m in the project.
The zero emission buses are able to cover long ranges and carry heavy loads, making them ideal for local routes around Gatwick that are intensively used – operating 24 hours a day, 365 days a year.
It will be served by a liquid hydrogen refuelling station in Crawley owned and operated by Air Products, the industrial gas company.
Once it reaches full capacity it will be the largest of its kind in Europe and will be capable of providing the equivalent of fuel for more than 100 buses per day.
The project has been backed by more than £4.3m of funding from the Government's Ultra-Low Emission Bus scheme.
Jean-Marc Gales, Chief Executive of Wrightbus, said: "Public transport is a key area in the UK's zero carbon ambitions and hydrogen has a vital role to play. Collaborations such as this one show the potential of UK industry to meet this challenge that we face"