The ceremony, starting at 11.00 CET (14:00 Yerevan Time) on Saturday, will be attended by the presidents of European Union institutions, former and current heads of state and government and other dignitaries.
EU Commission President Jean-Claude Juncker said the ceremony at the European Parliament's seat, close to the border with Germany, was Kohl's own choice, describing him as "a German patriot and at the same time a European patriot".
The two-hour memorial took place in one of the EU's three working parliaments, in a city that has passed between Germany and France several times, a symbol of sorts to inspire European integration.More news: Father Arrested for the Murder of His Missing 5-Year-Old Son
After a memorial in Strasbourg, France, Helmut Kohl's coffin is transported to Speyer, Germany, where he will be buried. With the former French president François Mitterand, he drove the...
Mr Kohl worked for German reunification as others hesitated, Mrs Merkel said, adding that his motivation was always that there should be no more war in Europe.
"Much of what we take for granted today we can thank him for: that Eastern and Western Europe are united, that we have a common market, that there are no border controls between European Union states and that majority share a common currency", said Angela Merkel, the current chancellor whom Kohl gave her first cabinet post.
Germany's longest-serving chancellor since 19th century leader Otto von Bismarck, Kohl took office in 1982 when the Soviet Union had an iron grip on eastern Europe. Mitterrand was cool initially but it was "all fire and flame" for Kohl after a visit to Paris, she said.More news: Sky not the force of old, says Tour rival Porte
Kohl married Kohl-Richter, 34 years her husband's junior, when he was 78.
That decision has been criticised by Walter Kohl, Mr Kohl's son by his first wife, who wanted a farewell ceremony near the Brandenburg Gate in Berlin, near the site of the former Berlin Wall.
Kohl is widely regarded as having skillfully overcome the fears of Germany's neighbours when an end to the country's decades-long division into a communist east and a democratic west first became a realistic possibility in the late 1980s.More news: Eastbourne 2017: Novak Djokovic eases into final by beating Daniil Medvedev
She also offered personal thanks for the opportunities that Mr Kohl - her political mentor whom she later denounced over a funding scandal - had given her in her career.