Petroineos has sent redundancy letters to some of its staff at Grangemouth refinery.
Scotland's only oil refinery, the site is to close its doors by this summer - at the cost of 400 jobs.
The job cuts are to be spread out over the next 18 months, but the majority of employees have opted to take voluntary redundancy, the BBC reports.
Unite the union, which had hoped the refinery would stay open and be used for greener fuel alternatives, has branded its closure a "national disgrace" and accused the UK and Scottish governments of being "missing in action" as the closure takes effect.
Meanwhile owner Petroineos explained the Grangemouth site was unable to compete with sites in Asia, Africa and the Middle East.
The facility is set to be converted into a terminal for importing petrol, diesel, aviation fuel and kerosene into Scotland, but that is only expected to support approximately 65 jobs instead of the roughly 500 currently there.