The issue was related to its payments services provider, Elavon
Retailer Penneys say an earlier issue with its credit card machines has been fixed.
Operator Primark confirmed there was a "temporary outage" in its Irish stores.
It said the issue was with its payments services provider, Elavon.
This caused a temporary outage with card machines in Penneys stores.
A statement added that this has now been fully resolved.