Taoiseach Enda Kenny has attended a special ceremony at Ardnacrusha Power station in Co Clare to mark the 85th anniversary of the founding of the ESB.
He honoured two of his predecessors at the ceremony, WT Cosgrave and his son, Liam.
Ardnacrusha was the country's first power station and was built at a cost of £5.2m by the German company Siemens.
That figure represented almost one fifth of the entire annual budget of the Irish Government at the time.
Construction work on the massive project employing 5,000 people began in August 1925 and the ESB was established by the Government in August 1927.
Ardnacrusha was formally opened by WT Cosgrave, the President of the Executive Council in the first Free State Government, in July, 1929, and he was accompanied at that ceremony by his son Liam who was nine at the time.
Mr Kenny will present Mr Cosgrave with a copy of a portrait of his late father by the artist Sean Keating, who is well known for his extensive artistic work on the Shannon scheme.
Liam Cosgrave went on to become Taoiseach in 1973 and led the Fine Gael / Labour Coalition Government until 1977.