Mars said it would support employees as they try to find new jobs
Forty-five jobs are under threat at the Mars factory in Slough, a month after the firm started work on a new £5.2m research facility at the site.
The chocolate firm said it needed to stay competitive and despite investment in the new facility, it had identified manufacturing roles that could go.
Construction started on the research and development site at the factory in Dundee Road in March.
Mars said it would be consulting and supporting affected workers.
A Mars spokesperson added: "Mars remains committed to producing chocolate confectionery at its Slough factory.
"Over £75m has been invested in the Slough site over the past four years.
"The recent plans to create a world class research and development facility, with an investment of £5.2m, is an example of the ongoing commitment to the Slough site.
"Mars is constantly looking for ways to improve its performance in providing high quality products to consumers.
"As part of this ongoing work, and in order to remain competitive, we have identified opportunities to improve parts of our manufacturing operation."
The new purpose-built centre will feature new offices, kitchens for preparing and creating products, and laboratories.
A pilot line at the facility will enable products to be test-manufactured on a larger scale.