Two one-day work stoppages are to take place at Ireland's largest research centre, the Tyndall National Institute in Cork, in an on-going dispute over pay.
About 460 researches and support staff work at the institute.
Last month, following a one-day work stoppage, SIPTU warned of further industrial action if progress on the pay disparity between its 70 members and their colleagues in UCC is not resolved.
They have now issued notice of two one-day work stoppages, the first of which is to take place on Wednesday.
Members of Irish Federation of University Teachers are also joining the protest.
Both unions have warned that a further one-day stoppage will take place the following week on Tyndall and on University College Cork, where SIPTU has about 800 members.
Last month at the Labour Relations Commission, officials from the Department of Education and from the Department of Public Expenditure and Reform failed to resolve the four-year dispute over pay.
In a statement issued at the time by UCC, the university said it greatly values its staff and acknowledged there should be no disparity of treatment between colleagues.
However, it said that any resolution had to be in accordance with current public pay policy and the Haddington Road Agreement.
The university also acknowledged that any industrial action poses significant financial and reputational risk to the institute.