He praised former British Prime Minister Margaret Thatcher for her honesty, even as he recalled a confrontation with her just days after the fall of the Berlin Wall.
"My mentor, my friend, the very essence of Europe, he will be greatly, greatly missed". "Helmut was a rock".
As "Chancellor of Unity", Kohl entered the history books.
Georgian Prime Minister Giorgi Kvirikashvili expressed his sadness over the death of former German Chancellor Helmut Kohl.
"I will never forget how in a dramatic meeting of the European Union in December 1989, it was not least the Irish prime minister who supported us Germans and myself in a very hard situation", said Kohl.
Kohl's Christian Democratic Union Party tweeted Friday: "We are in sorrow. The world has benefited from his vision and efforts".
Gerhard Schroeder, Kohl's successor as chancellor, called him a "great patriot and European.The unification of our country and our continent will be linked to his name for all time".
Four tied for lead in US Open
McIlroy , the No. 2 player in the world, also arrived last Friday having missed the last month to rest a nagging rib injury. And if that's not enough of a traffic jam at the top, 18 players are separated by three shots to start the third round.
Despite their differences, Merkel made clear on Friday that Kohl had touched her life deeply when he helped forge a united Germany.
Speaking in Rome yesterday, Merkel said her predecessor's skilful statesmanship won over Germany's neighbours and ensured a peaceful reunification.
The Kremlin said Russian President Vladimir Putin had sent condolences to Germany's president and to Merkel and cited him as saying Kohl "will be remembered in Russia as a resolute supporter of friendly relations between our countries".
Famed for a massive girth on his 1.93-metre frame, Kohl still moved nimbly in domestic politics and among rivals in his conservative Christian Democratic Union, holding power for 16 years.
World leaders have paid tribute to Helmut Kohl, the former German chancellor, who died yesterday aged 87.
Often harsh and thin-skinned, Kohl also could display a quick wit and jovial earthiness.
FILE - The July 17, 1990 file photo shows Soviet President Mikhail Gorbachev, center, sitting with West German Chancellor Helmut Kohl, right, and German Foreign Minister Hans-Dietrich Genscher at a table in the garden of the guest house in Archiz during a break in their talks on the discussion of NATO-membership of United Germany, the most hard topic in the negotiations to German unification. During his term in office, the Berlin Wall fell and the German reunification was completed peacefully after over four decades of division.