One hundred zero emission buses are set to go into service in Northern Ireland over the next two years.
Twenty of them will be hydrogen powered and the other 80 will be battery operated.
Representing an investment of £66m by the Department for Infrastructure, the programme will include the buses and associated infrastructure supplied by local firm Wrightbus.
The Department said in a statement that these are the most environmentally-friendly buses on the island of Ireland.
The buses will be deployed between Metro in Belfast and Foyle Metro services in Derry. There will also be 45 low emissions buses for Ulsterbus services across Northern Ireland.
The first three hydrogen-powered double decker buses ordered earlier in the year are due to enter passenger service before the end of 2020. The buses will only emit water.
Infrastructure Minister Nichola Mallon said: “Cleaner, greener, sustainable transport is key to protecting our environment and fighting the climate crisis. I have an ambitious vision for a low carbon future where we make low emission public transport accessible to people and communities across Northern Ireland.
“This marks a very positive step forward that will create jobs, encourage investment, as well as being pivotal in cutting the level of emissions.
“As well as reducing pollution, the new vehicles will have additional safety features and improved comfort and accessibility, helping to grow passenger numbers, increase overall customer satisfaction and make public transport a more attractive and efficient alternative to private cars.”