He predicts the Madrid summit will be an overwhelming success: Nato leaders will finally name the countries that have made the grade to join in the first expansion wave, demonstrating once and for all the West's commitment to end Cold War divisions. "It will be quite a happening," he says.
Privately, however, he must be worried. In past days he has worked the diplomatic channels, calling alliance leaders, including Tony Blair, to try to avert a row at Madrid. The clash is looming over which countries should be declared winners in Nato's membership contest - or, as others are describing it, Nato's "oriental bazaar".
Washington, which wants just Poland, Hungary and the Czech Republic in the first wave, is at loggerheads with France, which wants Romania in, and Italy, which wants Slovenia. How other alliance members will line up is not clear but political interests are certain to play a key role. The US has angered some Europeans by demanding a limit of three starters, largely because wider expansion would not be approved by Congress. Britain backs the US, while the Scandinavians want a place in the first wave for at least one of the Baltic states.
Estonia, which has qualified in many eyes, is bitter at the prospect of being left out at the start, and Romania says a decision to exclude it first time round would be "cynical."
The squabbling has also sent a signal of Nato weakness to Moscow. On the eve of Madrid, President Boris Yeltsin refused to attend, snubbing Nato a month after appearing to soften opposition to expansion by signing a co-operation pact in Paris.
Mr Solana believes a deal can be done which will please all sides. "It will have to be three members, four members or five." He also believes those left out in the first wave will be reassured by the promise of a second wave soon after. "Everyone must understand that Madrid is the beginning of the process, not the end. Sometimes people think this will be the end. But it is not true that those who don't get in this time will never get in."
But more is at stake than simply names on a list. The Madrid summit comes at a time when Western enthusiasm for bringing former Eastern Bloc countries in from the cold has been tapering off within Nato and the European Union.
Last month's Amsterdam summit on reform of the EU demonstrated its lack of vision and doubts about enlargement by failing to agree on changes to institutions which would accommodate new members.
Now many leading EU political figures are questioning whether Amsterdam achieved enough to allow enlargement to go ahead on time.
Divisions at Madrid would show that Nato too is in a quandary about how to manage enlargement, showing that it is more intent on its own squabbles than on achieving more high-minded objectives. One of Nato's prime objectives since Mr Solana took over in 1995 has been to secure a stronger role for the European arm of the alliance, a move boosted by France's declaration that it intended to rejoin the integrated military command structure.
But France has said it no longer intends entering the Nato core grouping, due to anger at refusal by the US to make key concessions. Mr Solana is finely tuned in to the transatlantic debate, having always been a strong advocate of securing a stronger European Nato defence capacity and a defence role for the EU. Today, however, he is determined to ensure nothing undermines Nato's passage to expansion. Questioned about its future role, given the demise of the Russian threat, he proffers the familiar vague warnings about deterring arms proliferation and defusing ethnic conflict.
But enlargement is clearly the objective for Nato which Mr Solana most fervently believes in. As a young socialist, Spanish membership of the alliance was anathema to him, but in today's changed world Mr Solana believes that "collective security" for the new democracies gives Nato's mission firm moral underpinning.
"Both the institutions of the EU and Nato have a responsibility to the countries of Central and Eastern Europe. Both have to open their doors - although at what velocity we will have to wait and see."Reuse content