A double-decker London bus powered solely by electricity will undergo tests in October, London Mayor Boris Johnson said.
"The iconic red double-decker bus is about to become greener than ever," he told the Clean Bus Summit earlier.
According to London Assembly Transport spokesperson Valerie Shawcross, it was "fantastic" news.
"With London's bus fleet contributing to the capital's ever growing air pollution crisis, we need a plan to make environmentally friendly vehicles the rule not the exception," the Labour member continued, digitalspy.co.uk reported
Passengers on route 16, between Cricklewood and Victoria Station, would test upto five purpose-built purely electric double-deckers in the autumn.
Transport for London (TfL) already operated 1,300 hybrid electric and diesel buses.
There were currently eight single-decker electric-only buses in operation on short commuter routes - six buses designed by British firm Optair and two made by the Chinese firm BYD which was also the supplier of the trial double-decker version.
TfL aimed to have 300 electric-only buses by 2020.
London was one of only a few cities in the world that operated double-decker buses, partly due to it being a London tradition, and partly due to the large number of people who use buses in the city, according to a TfL spokesman.
The mayor aims to cut bus emission in half by the end of his term in office in 2016 as against the levels in 2008.
"It's essential because the air in your city isn't clean enough," London's transport commissioner Peter Hendy told The Guardian.
"But it's only going to be possible if the prices are affordable and the operating costs bearable."
All-electric double-deckers were earlier deemed as too challenging due to the size and weight of batteries needed to power vehicles of the size.
"The iconic red double-decker bus is about to become greener than ever," Johnson said. "I could not be more pleased that London will play host to these exciting pure electric double-deck buses, and I'm sure the lucky users of route 16 will embrace it with gusto."
London and 23 other cities have planned to roll-out 40,000 low-emission buses by the end of the decade at a global clean bus summit in City Hall.