Those attending the event starting Friday in the west German city include Filip Dewinter, head of Belgium's far-right Vlaams Belang party, and Andreas Mölzer, the Euro MP once ejected from Austria's Freedom Party for being too extreme.
Also adding his support to what organisers call Europe's "shared, thousand-year history", identity and "Western values and Christian traditions" will be Mario Borghezio from Italy's anti-immigration Northern League. Jean-Marie Le Pen, the veteran head of France's financially stricken Front National who has several past convictions for racist and anti-Semitic outbursts, has declined an invitation to attend, however.
The rally is being organised by the far-right Pro-Köln (For Cologne), which says it on its website that "half a dozen" coaches have been hired to bring supporters from Belgium. A "high-ranking delegation" is also expected from Austria, as are supporters from Italy, Spain and Britain, it says.
Pro-Köln hopes 1,500 people will attend the high point of the two-day congress, a rally in the city centre starting at noon on Saturday, and police say they expect several hundred. But their numbers will be dwarfed by 40,000 to 60,000 people that Cologne's mayor hopes will gather for one of the 20 or so planned counter-demos that are also expected to attract supporters from other European countries.
Mayor Fritz Schramma, whose city council recently gave the green light for the construction in Cologne of what will be one of Europe's biggest mosques, has called on the city's inhabitants to show the far-right "the cold shoulder."
"Shut your windows and doors, lower your shutters ... Make it clear to Pro-Köln and its camarilla: you are not welcome in Cologne," Schramma said in a statement.
"Cologne is a city for Christians and Muslims, for people with and without religion. Our city is renowned for its variety and its tolerance ... Populist right-wing rat catchers openly in favour of exclusion and who stir up fear are not welcome here," he said.
He also called for demonstrators to refrain from violence - but police are taking no chances. They plan to deploy around 3,000 officers to prevent and break up any clashes in the city centre's narrow cobbled streets and alleyways.
"We have prepared very well for this ... We will not tolerate any violence," police chief Michael Temme said, admitting however that the mission will be "very difficult."
The US Embassy issued a statement advising Americans to "defer non-essential travel to Cologne at this time."
Those attending the conference may find it hard to get a glass of Cologne's famous Kölsch beer, with 150 of Cologne's bars putting up banners promising "No Kölsch for Nazis." Some 200,000 beer mats have also been printed with the same message.