A full hearing of the Labour Court to try to resolve the health workers row is underway.
A three-day strike by 10,000 support staff at hospitals and healthcare facilities was deferred this week after the Labour Court intervened in the dispute over pay.
Siptu's Paul Bell says he hopes the court will make an acceptable recommendation.
"The mood is that we are in here to fight for pay justice for our members," said Mr Bell.
"We believe that the Labour Court have a massive role to play in helping us to reach a resolution to a very serious dispute.
"We look forward to putting all of the issues of concern for our members to the court for consideration."