The staff, mostly women, provide catering and retail service across the trust.
They transferred to Sodexo in January 2018.
Sodexo have refused to pay the three year NHS Pay Deal, costing UNISON members £1000’s.
UNISON members will be taking action on May, 1, 2, 3, 7, 8, 9, 15, 16, 17, 20, 21 and 22.
Hard working UNISON members have been left with no alternative other than to pursue industrial action.
UNISON members have called on their colleagues in the Trust to bring ‘Sarnies for Solidarity’ on strike days to show their support for their campaign for fair pay.
A UNISON member said: “We feel we have no choice but to take this action, we can’t afford not to.
“Many of us have worked for Trust for many years but we are now amongst the lowest paid staff in the NHS.”
A spokesperson for Sodexo said: “We acknowledge the right of our employees to participate in industrial action.
“The continued care of patients at the hospital is our top most priority during the planned industrial action.
“We have contingency plans in place and will work closely with the Trust to minimise disruption in the delivery of services to patients.”
Sue Cookman, UNISON Regional Organiser, said: “Striking is always a last resort, but our members have been left with no alternative as Sodexo have refused to honour their agreement and negotiate with us locally.
“Our members are standing up for their rights and for members elsewhere in the country. These members, who earn between £17,000 to 18,000 a year, have been forced to a ballot because the company simply refuses to speak to us constructively.
“We raised this issue eight months ago with Sodexo but there has been no movement to resolve the issue.
“This is a company that last year made almost £1billion in profits yet they refuse to meet their basic responsibilities to staff.
“UNISON has also raised this with the government, urging them to put pressure on the company to pay the nationally agreed pay award.”
A spokesman at Doncaster and Bassetlaw Teaching Hospitals said: “We hope that Sodexo and UNISON are able to reach a resolution as soon as possible.
“In the coming days and weeks it will be our priority to work with both Sodexo and our union colleagues to minimise any disruption to our patients.”