"We are in sorrow. #RIP #HelmutKohl," his Christian Democratic Union Party posted on Twitter.
Germany's Bild newspaper reported Mr Kohl died at his home in Ludwigshafen, the Rhineland city where he was born in April 1930.
Mr Kohl was the country's longest-serving post-war chancellor, leading Germany for 16 years from 1982 to 1998.
He is fondly remembered as the man who brought East and West Germany together after the fall of the Berlin Wall in 1989.
Despite the misgivings of allies about the danger posed by a reunited Germany, Mr Kohl drove forward with plans to bring together the two halves of the nation, split in two after the second world war.
In 1990, East and West Germany and the four World War II allies (Britain, France, USA and USSR) signed the "two-plus-four" agreement, sanctioning German reunification.