Tomorrow morning's official arrival ceremony in Brasilia will be a formal affair with national anthems, flags and troops lined up for inspection by the Taoiseach. However, this is not simply a ceremonial visit: there is a substantial agenda, dominated by economic and business matters.
The Taoiseach, accompanied by his partner, Celia Larkin, will spend eight days in Brazil and Argentina promoting business and trade links and developing political relationships with a region seen as ripe for development as a major market.
However, he arrives just as economic storm clouds gather over both countries. For if the Taoiseach is facing into a difficult budgetary process at home in the autumn, it is nothing compared to the political and economic difficulties faced by the man he will meet for an hour this morning, Brazilian President Fernando Henrique Cardoso.
Having steered through major freemarket economic reforms over the past few years, President Cardoso - now entering the last months of his second and final term as president - is seeing much of his work in danger of unravelling.
Energy shortages have led to electricity rationing in Brazil and almost daily power cuts; foreign investment has slowed down; Brazil's currency - the real - has lost more than 22 per cent of its value so far this year; the country's central bank has cut its forecast of economic growth for 2001 from 4.5 per cent to 2.8 per cent.
The Brazilian government blames the lack of rain for the energy problems; the opposition blames the government's handling of electricity privatisation. The economic crisis in neighbouring Argentina - to which Mr Ahern will travel at the weekend - has also contributed. In parallel, Brazil's ruling coalition has been shaken by corruption allegations.
There is growing public disillusionment and a belief that the candidate of the growing left-wing opposition is now in a strong position, in advance of the forthcoming election, of becoming President Cardoso's successor.
The idea behind the Taoiseach's visit is to secure mutually beneficial trade and business links over a timescale that will stretch beyond the present economic difficulties. Brazil, Argentina, Chile and Mexico are all facing economic problems. South America in general and Brazil in particular remain places of huge untapped potential, in the eyes of international capital.
In recognition of this, Mr Ahern will tell President Cardoso of the Government's decision to open a residential embassy in Brazil, following Brazil's opening of one in Ireland some years ago. The new embassy will become only Ireland's second in South America (the other is in Argentina.) With the diplomatic service already expanding with new embassies in the applicant EU states, the move shows how important the country is seen as a potential market and influential player in the region.
The Taoiseach and the President will discuss the political and economic situation in Brazil, while the Taoiseach is likely to give his host a briefing on the situation in Northern Ireland.
While there has been no significant political relationship between the two countries up to now, the growing economic relations between the EU and South America makes the development of political relationships more important.
There is a very limited Irish business presence in Brazil and just a few hundred Irish - many of whom are missionaries - living in the country. The Kerry Group operates two plants there, and ESB International, as well as Eircom's international division, are active in the country. However, other Irish business involvement is very small. In 2000, Brazil was Ireland's 39th largest export market.
The trade figures show that the State exported £162 million worth of goods to Brazil, mainly computers, office machinery and other high-tech products. However, many of these exports are goods produced by foreign-owned multinationals operating in Ireland. Meanwhile, the State imported £100 million worth of goods from Brazil.
On Thursday in Sao Paolo - Brazil's business capital - and on Friday in Rio de Janeiro, Mr Ahern will give economic speeches to business audiences. The view of government and business organisations is that there is huge potential to expand the value of goods exported to Brazil, particularly in the areas of computer software and telecommunications.
Brazilian business is alive to the prospect of increased trade between the two countries as well. The Federation of Industries of the State of Rio de Janeiro is to visit Dublin later this year.
Brazil, in common with the rest of South America, is hugely dependent on foreign capital. The development of strong, indigenous exporting industries is seen as the key to lasting growth - hence the desire to penetrate EU markets such as Ireland.
Brazil's population of 171 million produces a per capita gross domestic product of £5,370, roughly a fifth of that of Ireland. It officially has 7 per cent unemployment, but considerably more people are underemployed and earning very little.
While the Brazilian people may have no great consciousness of Ireland, this is not true of Argentina. Of that country's 36 million population, some 500,000 are of Irish descent. Most of their Irish ancestors emigrated from the 18th century onwards to what was one of the richest countries in the world with great opportunities for those with knowledge of farming.
The Taoiseach marked the historic Irish connection shortly after his arrival on Sunday by laying a wreath at the statue of Padraig Pearse in Buenos Aires's Plaza Irlanda. Today he will lay a wreath at the monument to the founder of the Argentine Navy, Admiral William Brown of Foxford, Co Mayo.
He will also lay a wreath at the Malvinas War Monument, commemorating the 1981 war with Britain over the Falkland Islands. The passage of time has removed any sensitivity that could have surrounded such a gesture in the past - several visiting EU leaders have previously laid wreaths at the monument.
If Brazil is facing economic difficulties, Argentina's are arguably worse. Once the economic star of South America, the country's output shrank by 3 per cent in 1999 and a further 1 per cent in 2000.
There is a limited amount of Irish investment in Argentina, with the Kerry Group active there as well as in Brazil. Cement Roadstone Holdings (CRH) has three plants in the country, while the Smurfit Group has a foothold through a US subsidiary. But as in Brazil, there is seen to be huge unexploited potential, particularly in the areas of financial services and education software.
In both countries, the Taoiseach will make not only important economic speeches but also keynote addresses on foreign policy which will cover Northern Ireland. He will also attend several receptions for the Irish communities of both countries.
And while the attempt by Irish business to engage substantially with the developing world is relatively new, other more traditional forms of Irish involvement in such countries have been around for a long time.
Mr Ahern will acknowledge this on Saturday, visiting an Irish Aid-funded project in a Rio de Janeiro favella, or slum, and during his visit will meet many of the Irish missionaries who were active in Brazil long before Irish business began paying attention to the country.