One hundred and thirty five jobs will be lost when the Elementis plant closes.
More than 100 workers at a Teesside chemical plant are set to lose their jobs when it closes.
Production at the Elementis Chromium site, at Eaglescliffe, will stop at the end of June.
A 90-day consultation is now under way with unions and staff to discuss the future of the 138-strong workforce.
Elementis said the plant had faced increasing competition from Asia. The Unite union said the workers had fought to try to save the plant.
Elementis announced in February it would be carrying out a strategic review.
It said: "The strategic review has now been completed and concludes that the Eaglescliffe UK plant will close with production ceasing at the end of June 2009.
"Elementis will finalise the closure programme in consultation with the employees and union representatives at the facility and details of this will be disclosed when then interim results are announced in early August."
'End of an era'
Unite regional officer Bob Bolam described the announcement as the "end of an era" and said workers saw it as a decent plant being cast adrift.
He said: "People have worked there for quite a few years so it is going to be a wrench.
"We are in talks with the company to try and ease the pain as much as they can.
"It's a sad day for Eaglescliffe."
He said the union was working to get the best deal for the workers.
The plant produces chromium which is used in timber treatment, the car industry and in leather tanning.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.