Hundreds of staff at the University of Sheffield have started a 24-hour strike over proposed pension changes.
Unions claim the lowest paid workers would see their pensions halved under the changes.
The university has said rising costs and low take-up raised questions about the pension scheme's "sustainability".
Cleaners, porters, caterers, clerical staff and security guards are among those who are involved in the walk out which started at from 0700 BST.
The Unite trade union said in a statement: "The university is ending the final salary scheme for workers on grades one to five, and replacing it with an inferior cash balance scheme.
"However, grades six and above will keep their defined benefit scheme.
"This is a huge blow to the lower paid members of staff."