Energy-linked price hikes, largely fuelled by the ongoing war in Ukraine and sanctions on Russia, have sent inflation to its highest rate in three decades in Greece.
"The cost of living is untenable," read a large poster for the country's biggest union, the GSEE, also calling for salary increases and "social protection for all".
Several unions have called rallies around the country for later in the day.
Prime Minister Kyriakos Mitsotakis' government has announced a 5.5-billion-euro package of aid which includes a 250-euro subsidy to 2.3 million vulnerable citizens in December and an increase in the student housing allowance.
But unions insist on the need for salary rises, not hand-outs, amid double-digit inflation in the last six months which rose to 12 percent in September.
