Born on March 3, 1930 in Oltenita, south of Bucharest.
He went to primary school in his native town, attended secondary school in Bucharest, then "Industrial-Polizu", "Spiru Haret" and "Sf. Sava" high schools. He graduated from the Electrical Engineering Faculty, Bucharest Polytechnic, and Energy Institute, Moscow, specializing in water management and ecology.
He started his professional career in 1955, as a designer engineer at the Institute of Energy Studies and Design in Bucharest.
Between 1979 and 1984 he chaired the National Waters Council. In that capacity he prepared comprehensive projects on Romania's water resources and their management. Since he consistently supported the scientific approach taken by experts and opposed the dictator's megalomaniac and wasteful programs, he was dismissed from office in 1984.
From 1984 to 22 December 1989, he was director of the Publishing House for Technical Literature in Bucharest. He encouraged publication of valuable books on modern science and technology, thus helping to break the international isolation to which Romanian scientists had been subjected by the communist regime.
In public life he always supported democratic thinking and openness to European political, scientific and cultural values.
In 1948, he was one of the founders of the Union of High School Students Associations of Romania, based on the principles of freedom and democracy.
The organization was subsequently dissolved following accusations of neglect of class criteria.
In 1956 he founded the Union of Student Associations of Romania, patterned after the national student unions in Western European countries. He participated in various international student meetings and conferences as representative of Romanian students.
He actively supported the new political trends in Romanian politics in the 1960's, towards asserting the country's sovereignty and independence in its relations with the Soviet Union, eliminating Soviet-like structures and methods from Romania's economic, political and cultural life, and its opening to the West. Between 1967 and 1971, a period of hopeful political developments, he was Minister for Youth.
During the extraordinary session of the Romanian Parliament in August 1968, he publicly condemned the Soviet-led invasion of Czechoslovakia and Brezhnev's doctrine of "limited sovereignty".
In 1971, when he was for six months a Secretary of the Communist Party Central Committee, he came into conflict with the "cultural revolution" line taken by Nicolae Ceausescu and the latter's growing personality cult. As a result he lost his slot in the party hierarchy and went to serve as Deputy-Chairman of Iasi County Council between 1974 and 1979.
Subsequently, he was effectively removed from the political scene. He was kept under strict surveillance by the Securitate, in political isolation, with limited possibilities of communication.
Nevertheless, his personality became ever better known among wider professional and social groups in Romania and abroad.
During that period he came to be widely regarded as a politician who could be trusted to lead the struggle against totalitarianism, for freedom, justice and democracy. His courageous attitude never wavered in the late 1980s, the darkest years of communist dictatorship. Western radio broadcasts, that were clandestinely listened to by many Romanians, greatly helped to dissipate the conspiracy of silence surrounding his name. It was no wonder, therefore, that during the days that preceded the collapse of the dictatorship, in Timiºoara, where he had worked for four years, and in other places throughout the country, the crowds in the streets chanted Iliescu's name.
In the early hours of the Romanian Revolution on December 22, he was called upon to lead the first post-communist body of state power: the National Salvation Front Council. On that day, he read on the national radio and television the first declaration to the country defining the targets of irreversible political and social change in Romania: to scuttle the communist totalitarian system, to remove the monopoly of one-party rule and to establish democratic political pluralism, to introduce the rule of law, to build a civil society, to restore human dignity and respect of human rights, to guarantee freedom of expression, association and assembly, to carry out economic reform and transition to a market economy, to ensure a wide opening of the country to the outside world. Starting December 22, 1989 he was President of the National Salvation Front Council.
Between February and May 1990, he presided over the Provisional National Unity Council, including representatives of all the political parties that came into being in January 1990.
On May 20, 1990 he was elected President of Romania.
In the presidential elections, on October 11, 1992, the first elections to be held in accordance with the new Constitution, he won 7,297,551 i.e. 61.5% of the 11,910,609 valid ballots. In the presidential election campaign he presented his own platform entitled "I believe in Romania's change for the better", which covered the essence of the political, economic and social motivations of the transition emphasizing action in favor of reform and a market economy, democracy, strengthening the rule of law and the civil society, the role of Romania as a balance and stability factor in this geographical area still in turmoil.
In the general and presidential elections, on November 3, 1996, Mr. Ion Iliescu was elected senator of PDSR.
The Extraordinary National Conference of the Social Democracy Party of Romania, on January 17, 1997 designated Mr. Ion Iliescu as President of PDSR, position in which he was re-elected at the National Conference of the party, on June 20-21, 1997.
In 1992 he published the book "Global Problems: Creativity", that brings together articles and studies related to his profession, ideas on the environment, the relation between the beneficial application of the technical and-scientific developments and the worrisome pace of depletion of non-regenerating resources, with irreversible effects on the planet's future.
In 1993 he published "Revolution and Reform", a book that is more a political meditation rather than a description of events going on since December 1989, seeking mainly to highlight the particular traits of the Romanian Revolution, against the background of the developments in the whole East-European space, and the integration of the transition processes in Romania in the aggregate of today's world political and economic processes.
His book "Romania in Europe and in the World" was published in 1994. It includes speeches, addresses to international organizations, articles and studies on Romania's foreign policy options, in conformity with the new trend of the Romanian political, economic and social life.
In 1995 he published three books: "The Revolution Lived" - conversations and appreciation on the December 1989 events; "Diplomatic Autumn" - consisting of presidential addresses in international meetings in the last part of 1994; and "Moments of History" - a compilation of documents on the December Revolution and subsequent political, economic and social evolution in Romania. The second volume of this series appeared in the spring of 1996.
In 1996 he published "Moments of History - Volumes II and III" and "Romanian-American Dialogues".
On December 20, 2000 he was re-elected President of Romania.
He speaks French, English and Russian.
He has been married since 1951 to Mrs. Elena Iliescu, an engineer, researcher in the field of metal corrosion.