Siptu workers will down tools next month over plans to introduce Labour Court recommended cost-saving measures, including pay cuts.
The strike action on Monday, August 25, comes in response to Irish Rail's decision to implement the new measures.
The company says it will introduce temporary pay cuts from August 24 - ranging from a cut of 1.7% for staff earning up to €56,000 per year - to more than 6% for those earning more than €100,000.