Solictor David Royden said a number of Somerfield staff had contacted him for advice following the recent restructuring and store closures.
Royden said many faced receiving lower redundancy pay than they had expected, adding: "I understand that more than 1,000 people could be affected. If we establish there's a case, we would issue a multiple party group action and represent them at a tribunal."
Somerfield spokesman said: "We're not prepared to engage with this man. There's been a huge amount of work under way at Somerfield and we have consulted with colleagues throughout the process.
"Our aim is to ensure the long-term jobs for our 50,000 employees."