The premier's delegation started off in Japan, moved onto South Korea and finished up in India, with green hydrogen dominating talks.

There were partnerships inked, including a deal to bring Japanese giant Hitachi in as the first private tenant to Bradfield in western Sydney, while Indian tech powerhouse Infosys will open an innovation lab in North Sydney.

Mr Perrottet spruiked green hydrogen as paving the way to the state's prosperity to Korean automotive firm Hyundai and Japanese company Iwatani.

"We don't want people filling up with oil from Middle East, we want people filling up with hydrogen from NSW," the premier told reporters at an Iwatani hydrogen refuelling station in Tokyo.

He said NSW had the scale and infrastructure to supply Japan, South Korea and other markets with 110,000 tonnes of green hydrogen annually by 2030 and to reduce its production cost to $2.80 per kg by 2030.

Green hydrogen refers to when the fuel is produced by electrolysis - splitting hydrogen from oxygen in water - using renewable electricity with zero direct emissions.

But the mission was haunted from the onset by the appointment of former deputy premier John Barilaro to a plum New York-based trade job with a $500,000 yearly salary.

The premier opened up two trade and investment offices in Tokyo and Mumbai to sell the state to investors, but that only intensified the barrage of questions about the hiring process that saw Mr Barilaro's selection waved through ahead of that of public servant Jenny West.

The ongoing upper house inquiry into the botched trade envoy position loomed large over the trip, which Labor leader Chris Minns pejoratively described as a "Contiki tour".

But that did not dissuade Mr Perrottet from making a pitch to voters that he deserved another term in the 2023 state election because he led NSW during a politically rocky transition.

"There's a lot of noise, but take me on my track record on what I've stood for and what I believe in, what I want to achieve and what I have achieved," the premier told AAP in an exclusive interview in Seoul.

The political pressure on the premier only grew with Trade Minister Stuart Ayres joining the delegation in India as it emerged both men's offices had been briefed that Ms West was a suitable candidate, with Mr Ayres personally signing off on a briefing.

Labor accused Mr Ayres of misleading parliament after he said no suitable candidate was found in the initial hunt to fill the role.

Documents recently tabled to the inquiry include an email sent by Investment NSW CEO Amy Brown in February in which she said she discussed a shortlist of candidates with Mr Ayres.

In the email, she said the minister requested adding a candidate to the selection process. The candidate's name has not been made public.

Another Investment NSW document shows Mr Ayres and Mr Barilaro met on or before June 16 - the day before it was announced the former deputy premier had won the role - and Mr Ayres had indicated he supported the appointment.

Mr Perrottet was grilled about whether he would sack Mr Ayres but he defended the embattled minister saying he was "very good" at his job.

However, he conceded the weeks-long saga had become "frustrating" for him, and overshadowed his first trade mission.

"Is it frustrating that you don't get the message out publicly when these other issues come about? Yes it is," a visibly exasperated Mr Perrottet told reporters on his last stop in Bangalore.

Referring once again to an independent review he commissioned into the appointment, the premier said he would "take action" without specifying what that would entail.

Mr Perrottet's political fortunes dwindled further in the last two days of the trip after bullying and workplace harassment were levelled against Fair Trading Minister Eleni Petinos, who is responsible for keeping the state's workplaces safe. She denies the allegations.

The premier was unable to market his trade mission with the twin scandals hobbling his momentum, but he urged voters not to lose faith in his government.

"People should trust government because there are good people in politics," he said.

"My job is not to do what's popular but do what's right".

Australian Associated Press