Mayor Ken Livingstone has unveiled London's first hybrid double-decker bus in a bid to make commuting in the city a greener experience.
The bus will produce 40% less emissions
Built at a cost of £285,000, the bus runs on a combination of diesel and electricity and will produce 40% less carbon dioxide (CO2) emissions.
The mayor said the bus was the first of a fleet that will make London "one of the world's most sustainable cities".
The hybrid bus will be on the road by the end of November.
Six single-deck hybrid buses are currently operating in London.
A battery pack, which is run by a Euro IV complaint Diesel engine, powers the wheels of the new hybrid bus through an electric motor.
Unlike conventional buses, energy generated from braking is recycled and used to charge the batteries.
Mr Livingstone said: "Creating a low-carbon bus fleet is an important part of our work to cut the emissions which are causing climate change."
He said the vehicles still needed a manufacturer and needed to be "financially feasible".
But he said it was a good opportunity for such a company.
"The first off the mark will get to corner the bus market until the others catch up with them - that should be a really attractive prospect."
The bus will be exhibited at the Euro Bus Expo 2006 in Birmingham next month.
When it returns to London it will operate on the route between Wood Green and London Bridge.