The Army ordnance disposal unit carried out on a device found in a wall on Slievnamon Road in Thurles this Monday evening.
The device was located after a member of the public contacted Thurles Garda station to state they had found a device in the wall of a building on a premises.
On arrival, Gardaí observed what looked like a grenade in a small opening in the wall and cordoned off the area.
Command and Control dispatched the Explosive Ordnance Disposal team to the incident.
At 18.30pm, the EOD team arrived at the scene and after examination a controlled explosion was carried out on the device.
It is believed the device had been there for a number of decades.
Traffic was stopped for at least 20 minutes while the device was made safe.