The no-frills airline will sell €10 seats, £8.20 at today's exchange rate, when it eventually manages to secure the long haul aircraft needed, O'Leary announced today.
The airline has a business plan ready for launching transatlantic flights but admits it will be several years before it can get the planes needed.
Mr O'Leary told the Irish Hotels Federation conference in Meath that Ryanair would offer €10 flights to the United States and US$10 flights from the US to Europe, though passengers would pay extra for everything from meals to baggage.
The flights would operate from 12-14 major European cities to 12-14 major US destinations and a full service would begin within six months of Ryanair getting the aircraft to do so.
However it would be four to five years before this happened as currently the Gulf state airlines are buying up all available aircraft.
Mr O'Leary praised the Republic's government for scrapping the travel tax to Ireland from April 1st as the single biggest step to boosting tourism to Ireland since it came into power.
He said Ryanair would deliver an extra 1m passengers to Ireland as a result creating an extra €300m in tax revenue to the government through increased tourism spending.
But he urged Transport Minister Leo Varadkar to sell off Irish airports to make them more efficient as had been done in most European countries.
Mr Varadkar hinted that privatising airport terminals while maintaining government ownership of the runways and ground areas could be an option, noting this was an option favoured in the US.