The recent closure of Irish and European airspace due to the Icelandic volcano cost airports in Ireland €8m, according to the Dublin Airport Authority (DAA).
The DAA - which operates Dublin, Shannon and Cork airports - said 3,200 flights were cancelled during the six days of restrictions.
Up to to 400,000 passengers travelling to and from Ireland were affected by the crisis.
"In truth we are still counting the cost as the ripple effect of cancellations and delayed travel is still working through the system," DAA Chief Executive Declan Collier said.
At the launch of its annual report today the DAA also revealed that passenger numbers at Irish airports fell by 13% last year to just over 26 million.
Excluding exceptional items, profits for the company fell fell by 51% last year to €38m, as the recession had a significant impact on its business both in Ireland and overseas, the DAA said.
Turnover declined by 13% during the year to €547m.
Taking into account a number of exceptional items, the group recorded an after-tax loss of €13m for the year, compared to a profit of €47m in 2008.
It was also revealed that the first passengers are expected to use Dublin Airport’s new Terminal Two in October as part of the testing process for the new facility.
Mr Collier said trial flights would use T2 from October in the run up to the opening of the new terminal in November of this year.
“The main construction phase of T2 is now almost complete and we will shortly begin a detailed series of operational trials to test all of the systems and processes in the new terminal,” he added.