Moody's Investors Service has today upgraded the credit ratings of both Bord Gáis Eireann and the ESB.
Moody's said the move follows the upgrading of the country's sovereign debt to investment status from junk status.
It added that it recognised the utility companies' rating had been constrained by Ireland's government bond rating.
Both the ESB and Bord Gáis were upgraded by one notch to Baa2, two notches above junk status.
Moody's said the upgrade for Bord Gáis reflected the the high proportion of earnings arising from its regulated networks and the low business risk profile of gas transmission and distributions.
It also said the company has stable returns under "well established and transparent regulatory frameworks" and a diversified debt portfolio and sound liquidity position with limited reliance on Irish banks.
It said the ESB upgrade reflected the significant proportion of its earnings that the company generates through its transmission and distribution operations as well as the low business risk profile of these networks and stable returns under transparent regulatory frameworks.
But it also said the ratings reflected the higher business risk profile of ESB's generation and supply business compared with its transmission and distribution operations; the challenges associated with a large capital investment programme; and the constraints on its credit quality as a result of the risks associated with being based in Ireland.