AT chief executive Shane Ellison said the technology would give public transport operators more flexibility and complement existing electric bus services.
The $1.175 million bus built by Global Bus Ventures (GBV) in Christchurch will run between Howick and Britomart and will be operated by transport operator Howick and Eastern for the initial trial.
It will use a hydrogen fuel cell to generate electricity along with batteries and the only byproducts produced will be water, electricity and heat.
Fuel cell electric buses are already commonplace in European cities including Stuttgart, Cologne, Frankfurt, Hamburg, Versailles and Rotterdam.
AT is looking at replacing the supercity's existing diesel buses with electric and hydrogen fuel cell vehicles, which are expected to cost between $150m and $200m.
It is also in talks with Taranaki-based Hiringa Energy Limited about building a hydrogen refuelling facility in South Auckland.
Ellison said the hydrogen fuel cell technology would allow its buses to travel further than fully electric vehicles on some of the city's longer routes before refuelling.
The capacity of the electricity network to handle both the increased use of electric buses and private electric vehicles was also another consideration. He said the use of hydrogen buses would help reduce demand for electricity.
He said that while it was still early days, AT may end up opting for a mix of both electric and hydrogen fuel cell buses on Auckland's streets.
Hydrogen fuel offers far greater flexibility for public transport operators and would complement battery electric services.
"They are all factors that are at play at the moment and why this trial is really important."
Ellison conceded there were other countries around the world that had gone much further down the path of using hydrogen fuel cell buses and emission-free public transport.
"It obviously takes a lot of political commitment and those cities where it has been adopted there has been a huge commitment made to tackling climate change," Ellison said. "But if you compare us with Australian cities we're doing pretty well."
In a statement, Auckland Mayor Phil Goff said the fact transport made up more than 40 percent of Auckland's emissions meant transitioning to low and zero-emissions vehicles was important to help the city achieve its climate change goals.
"With the right infrastructure, hydrogen has the potential to power our buses and other parts of our vehicle fleet, which will help reduce emissions and lower air pollution in Auckland."
Transport and urban design blog Greater Auckland editor Matt Lowrie said the biggest hurdle in changing the city's bus fleet to more environmentally sound options was the upfront cost.
"They have lower operating costs, but they still take some time to pay for themselves," Lowrie said.
He said New Zealand had lagged behind other countries in adopting emissions-free public transport buses, which he put down partly to funding.
Lowrie said most of Auckland's bus fleet was replaced between 2015 and 2018 and involved buying new diesel buses at the time. But things had changed markedly since then both locally and internationally.
"As part of those contracts AT didn't require operators to have electric and emissions-free buses. And it was probably a year or two before electric buses became more mainstream," Lowrie said.
"By the end of the decade those buses will be coming to the end of their useful lives."
"We need zero emissions buses as soon as possible," Lowrie said. "There's lots of technology out there and I think AT is trying to find the right one going forward."
