He comes to these tasks after a distinguished career as a diplomat, concentrating on development and United Nations issues, including service as UN Commissioner for Namibia in 1977-1981, where he worked closely with a number of gardai and diplomats.
Before his election he was secretary of state at the Ministry for Foreign Affairs and a senior participant in the conference on former Yugoslavia.
Since his election he has travelled extensively, most recently to China, a fact which has occasioned some domestic criticism. He is unapologetic, saying that part of his job is to promote exports, another to encourage international dialogue.
He was criticised, too, before his election for not knowing enough about Finland's steep levels of unemployment; he vehemently denied this and has sought to contradict it by an energetic involvement in the issue.
While in Ireland he will visit, and hopes to learn from, a jobs partnership scheme in the south inner city area of Dublin which draws on community, business and trade union co-operation, using EU funds. Last week he intervened in a dispute between Finnish trade unions and the government over welfare cuts, helping to head off a general strike.
Interviewed in the new presidential palace outside Helsinki, a masterpiece of modern Finnish architecture, Mr Ahtisaari said he looked forward to hearing from the Government about its plans for the Irish EU presidency, including on unemployment.
The two countries have a good deal in common in approaching the Inter-Governmental Conference - to protect the interests of smaller states, to share the experience of running an EU presidency and to ensure that Finland's and Ireland's experience of UN peacekeeping and crisis management is effectively drawn upon in the European context.
Mr Ahtisaari is struck by "the enormous intellectual and strategic changes that have taken place in Europe since the end of the Cold War". Finland used the opportunity to clarify its position in Europe, thereby bolstering its security. But it holds out for an independent defence, born of the bitter experience of fighting alone against the Soviet Union in the Winter War of 1939-1940.
EU membership has reinforced Finnish self-confidence and identity in relation to Sweden and Russia, as it did Ireland's in relation to Britain. "We now have a more natural relationship with Russia. Finns would be surprised if you were to say they are afraid of Russia or Russians" rather than of specific problems, such as nuclear plants. Trade is picking up again and border security holds better than before.
"We feel very strongly that the exclusion of Russia would be a disastrous development. If we want peace then we have to have the Russians here." This means steady, quiet dialogue and a commitment to the general principle that "changes in Europe should not weaken its security or lead to new dividing lines".
Mr Ahtisaari will not comment directly on the issue of Nato versus EU enlargement. "Those who want to join Nato should have that right." He has put it to Russian leaders that they too must examine why states in central and eastern Europe which want to join Nato should genuinely feel so insecure. For Finland this is a crucial matter, given its sponsorship of the Baltic states as prospective EU members, especially Estonia, with which it has very close political and economic ties.
Finland and Sweden have recently put forward a paper for the IGC in which they argue that all EU states should have an equal right to be involved in setting out a mandate for peace- keeping and crisis management tasks undertaken on its behalf by the Western European Union. This is to ensure that those states that are not members of an alliance have the right to participate and influence security arrangements.
Finland, unlike Ireland, has joined the Partnership for Peace organisation associated with Nato, but does not intend joining the alliance, Mr Ahtisaari says. He is most impressed with the Implementation Force in Bosnia - Ifor - in which Finnish troops serve with Nato forces.
"Laboratory is absolutely the right word to describe this. Ifor shows that whatever your choice is about joining an alliance, you can still make a contribution" to European security.
Since Finland joined the European Union last year, a decision he supported and campaigned for, new procedures have been elaborated for sharing responsibilities with the prime minister and his cabinet to reflect the dual domestic and international nature of EU business.
They have a streamlined and open quality that might make many Irish parliamentarians and citizens envious. Mr Ahtisaari meets the relevant cabinet committees every week to discuss policy and the forthcoming week's agenda. The parliament's EU committee is briefed about it too, so that it keeps abreast of the running EU agenda.
The dual representation of president and prime minister enhances Finland's influence at EU Council meetings. It is a case of "two instead of one", Mr Ahtisaari says, in a confirmation that his country is taking rapidly and naturally to its new international involvement.