Staff at the Tunnock's factory in Uddingston, South Lanarkshire, have voted to strike in a dispute over pay.
It is understood that about 500 employees will take part in the 24-hour industrial action.
A mass meeting of staff is planned for Wednesday amid warnings that further strike action has not been ruled out at the factory.
The plant, founded in 1850, produces well-known confections such as Teacakes and Caramel Wafers.
Unite regional officer, Tony Devlin, said: "Our members are furious at their management's audacity to put out false and misleading information regarding any offers made. No formal offers were made.
"We have continually said that if a sensible offer with no conditions is made, then we shall put that to our members for them to decide.
"Our members are determined to get a fair and improved pay offer."
