Kohl led Germany for 16 years (from 1982 to 1998). He is credited with bringing East and West Germany together after the fall of the Berlin Wall, the BBC reports.
Together with his French ally President Francois Mitterrand, he was responsible for the introduction of the euro.
European Commission chief Jean-Claude Juncker has ordered flags at EU institutions to be flown at half-mast.
German Chancellor Angela Merkel, Kohl’s former protegee who later called for his resignation over a political funding scandal, said his death filled her with deep sadness.
“Helmut Kohl’s efforts brought about the two greatest achievements in German politics of recent decades – German reunification and European unity,” she said.
“Helmut Kohl understood that the two things were inseparable.”