Thyssenkrupp Nucera on Tuesday posted record quarterly sales, citing rising demand for its electrolyser technology as the hydrogen firm remained upbeat about the sector's prospects despite regulatory uncertainty.

First-quarter revenue for the three months to December 31 rose by more than a third to €208-million ($224-million), mainly driven by the group's alkaline water electrolysis division, which comprises the fast-growing green hydrogen business.

CEO Werner Ponikwar played down concerns over proposed rules for hydrogen projects in the US, a key market for the industry due to the availability of tax credits, saying customers were not overly worried.

The US last month asked hydrogen producers to prove they have used clean electricity built within three years of a hydrogen plant going into service in order to get credits, stoking fears that the sector's expansion could be slowed down.

"We don't see that our clients and potential clients are very concerned about those developments. We believe ... most of them can live very well with that. And we're also seeing now that projects are progressing in their development," Ponikwar told analysts.

Thyssenkrupp Nucera shares were up around 1% at 15.09 euros at 0845 GMT but have retreated from their initial listing price of 20 euros last July.

The company, in which both Thyssenkrupp and De Nora hold stakes, confirmed its annual outlook, saying it still expects an operating loss of tens of millions of euros due to ramp-up costs.

That corresponds with analysts' expectations of a loss of €45.6-million, LSEG data shows.

Shares in hydrogen companies have been volatile in part due to project delays and start-up costs for a nascent technology that still requires subsidies to be profitable.

Thyssenkrupp Nucera has remained bullish on the sector, saying in December that all its projects remain on track and on schedule.