Current President Joachim Gauck announced Herzog's death on Tuesday, without giving details. In a message to Herzog's widow, he described the former head of state as "a distinctive personality" who "advocated readiness for reform and at the same time stood for preserving the tried and tested."
Herzog, a jovial Bavarian, served as the chief justice of Germany's highest court before winning the presidency in 1994, four years after reunification.
He was one of the first leaders to address Germany's resistance to reform and its growing economic stagnation at a time when veteran conservative Chancellor Helmut Kohl's 16-year tenure was coming to a close. Germany was struggling with double-digit unemployment, amid worries that its labor market was too inflexible.
Herzog drew an unfavorable comparison between the dynamism of Asia and the stagnation in Germany, pointing to problems with bureaucracy and regulation, and a resistance to change.
"Germany must feel a jolt," Herzog said in a 1997 speech, urging Germans to set aside greed and pull together to overcome "a sense of paralysis."
"Pessimism has become a normal mindset in our country," he said. "Those who want to delay or prevent major reforms need to be aware that our nation will pay a high price for this."
However, the president, while seen as the nation's moral conscience, has a largely ceremonial job and reform was slow to come.
The following year, center-left Chancellor Gerhard Schroeder came to power saying that one of his government's tasks would be to modernize the country and deal with a "reform backlog." But it would still be several more years before Germany embarked in earnest on painful reform of the welfare state.
The reforms that Schroeder finally implemented were unpopular at the time, but they have been widely credited with putting Germany in good shape to weather economic crises.
Herzog — who succeeded Richard von Weizsaecker, remembered for urging his country to confront its dark past — also instituted an annual day of remembrance for the victims of the Holocaust, setting it on Jan. 27, the anniversary of the Auschwitz death camp's liberation.
Announcing the decision in 1996, he said remembrance must "remind future generations to be vigilant." Germany's Jewish community praised Herzog's commitment to ensuring that Nazi atrocities not be forgotten.
Herzog also reached out to countries that suffered under Nazi occupation, pleading for forgiveness when he traveled to Poland on the 50th anniversary of the 1944 Warsaw Uprising.
He spoke out firmly against lingering property claims by some Germans in regions that were part of Germany before its borders were moved westward at the end of World War II.
Herzog left office when his first term expired in 1999 and was replaced by Johannes Rau, a member of Schroeder's Social Democrats.
Herzog was born April 5, 1934, in Landshut in Bavaria. His father worked at a snuff factory and later directed the local museum.
Herzog studied law at Munich University. He was brought into politics by Kohl, then governor of Rhineland-Palatinate state, who named him the region's chief representative in Bonn in 1973.
He later served as culture minister and interior minister in the southwestern state of Baden-Wuerttemberg.
Herzog was named vice president of the Federal Constitutional Court in 1983 and was elevated to chief justice in 1987.
Herzog is survived by his second wife, Alexandra.
(AP)