SIPTU has said it was approaching talks aimed at resolving a dispute over pay and conditions for retained firefighters with "extreme caution".
For the last ten weeks, around 2,000 of the part-time personnel have been engaged in rolling industrial action, with pickets placed across 200 retained fire stations.
Members of the service, who are represented by SIPTU, are paid an annual retainer for being on-call.
They recently rejected a Labour Court recommendation aimed at ending the row, a proposal they described as a major disappointment.
The Labour Court had recommended that their retainer be increased by between 24% and 32.7%.
Under the proposals, a firefighter on an annual retainer of €8,870 would see it rise to €11,769.
The fresh negotiations involving the union and management got under way at the Workplace Relations Commission (WRC) in Dublin this morning.
It comes after the Minster for Housing and Local Government Darragh O'Brien issued a letter on Monday asking the parties to reconvene under the auspices of the WRC.
Speaking on the arrival of the SIPTU delegation, divisional organiser Karan O Loughlin said: "The resilience of the firefighters in this dispute is very evident now, so we're going to sit down with the other side today."
She said the retained firefighters have "always been willing to talk", but she said the SIPTU delegation is "approaching the meeting with extreme caution because the other side have been so rigid in their position to now".
"So, we don't want to build any expectations from today, but we are going to engage in good faith."
Ms O Loughlin said: "We're at a critical juncture in this row now, in this dispute, I think today will tell a lot."
The union members escalated their campaign of industrial action last Saturday, with fire stations going dark, meaning there is no internal communications with management apart from lifesaving information.
As part of the ongoing dispute, 50% of retained fire stations around the county are also closed on a rotational basis.
SIPTU said if the latest move did not encourage management back to the talks table, then from this Saturday, an additional one station would close each week, in each county.
Ms O Loughlin said: "The firefighters are resilient and we did serve notice of an escalation but the purpose of that escalation was to get negotiations started, it's not an end in itself, so it served its purpose."
Asked if progress was expected at today’s talks, she said, "It is too early to say.
"We've been here before, we've been with the Labour Court etc, and expectations were high around reaching a resolution.
"It didn't happen then, but there needs to be a resolution at some point but it needs to be a resolution that's acceptable to the firefighters otherwise the dispute will go on."
