Armed officers forced a car to stop on Spring Garden Street in Ballybough at about 18:00 on Friday.
They discovered what they believe to be a quantity of detonators and Semtex explosives.
The surrounding area has been cleared and cordoned off and an army bomb disposal team is attending.
The two men are being held under Ireland's Offences against the State Act and can be questioned for up to three days.
Two men have been arrested after explosives were discovered by police investigating dissident republican activity in Dublin.