Some 3,500 delegates are expected to attend the event, which will be addressed by the HDZ leader, Prime Minister Ivo Sanader.
Ten European prime ministers, leaders of centre-right parties, are expected to address the convention via video link. They will include Chancellors Angela Merkel of Germany and Wolfgang Schuessel of Austria, Prime Ministers Silvio Berlusconi of Italy, Janez Jansa of Slovenia, Mikulas Dzurinda of Slovakia, Kostas Karamanlis of Greece, Jan Peter Balkenende of the Netherlands, Jean-Claude Juncker of Luxembourg, Aigars Kalvitis of Latvia, and the head of government of the German state of Bavaria, Edmund Stoiber.
It has also been announced that Wilfried Martens, head of the European People's Party, the strongest political group in the European Parliament, will be in attendance.