Consumer goods giant Unilever says it's planning to invest £40m in its biggest factory at Port Sunlight on the Wirral.
But the firm is also planning to close sites, including factories in Swansea and Slough, with the loss of up to 800 jobs.
Around 150 new jobs will be created at Port Sunlight and other roles will be transferred there. The Merseyside workforce will grow from 1,500 to 2,000.
A distribution site in Bridgend and an office in Ewole, North Wales, will also shut.
Port Sunlight is Unilever's "historic home" and is where William Hesketh Lever, founder of Lever Bros, first opened a factory.
The proposed changes, to take effect by the end of 2013, could lead to 500 direct job losses and around 300 contractor and third party jobs.
Some jobs will also be outsourced to Unilever's IT centre in Bangalore, India.