The Air Corps is to get six new helicopters to replace ageing models in a €60 million deal.
Two light EC-135 helicopters will be bought from the Franco-German company Eurocopter, while four heavier AB139 models will be acquired from the Italian-UK firm Bell Augusta.
The Minister for Defence, Mr O'Dea, said he would sign the contracts in January.
"I am delighted that the negotiations have been concluded successfully and I look forward to these helicopters coming on stream over the next three years," he said. "The Air Corps are performing a superb job and deserve the very best of equipment to support them in their work."
The Air Corps currently has 13 helicopters, including Alouette models which are up to 40 years old. Some helicopters might be sold off when the new models come into service next year.
The two light utility Eurocopter models will be used for pilot training.
The four heavier Bell Augusta helicopters will be used for troop transport, inland search and rescue and air ambulance duties.
The Department of Defence had originally planned to purchase the helicopters in 2001. It entered into final negotiations with the United States arms company Sikorsky, which had promised to provide €125 million of work to safeguard jobs in the Dublin maintenance company FLS Aerospace.
However, Eurocopter, which had been recommended by the Department of Defence's expert group, began a legal challenge in the High Court to prevent the contract being awarded.
The former Minister for Defence Mr Smith scrapped the contract when budget cutbacks were introduced after the 2002 general election.