In most cases the amount of plutonium was exceedingly small - much less than that needed to make a nuclear weapon - and was used in research as part of the Atoms for Peace programme, according to the department.
The exports, never previously revealed, are contained in a wide range of documents and previously classified records to be released by the department as part of a promise by President Bill Clinton for more openness on nuclear issues now that the Cold War is over.
The Energy Secretary, Hazel O'Leary, has campaigned for wider disclosure of the country's atomic secrets. Earlier she released a list of nuclear weapons tests conducted in Nevada during the Cold War, information previously kept secret.
It has been widely assumed by private experts that the US has about 100 metric tons (110 tons) of plutonium in weapons, storage and as highly radioactive waste at weapons plants. In its latest inventory, the department put the figure at 99.5 metric tons (109.7 tons).
Never before revealed, however, was the extent to which radioactive plutonium, which can be used in nuclear weapons, has been made available to other nations, including some now considered unfriendly.
While the US shipped nearly a ton of plutonium abroad over the past 50 years, it also imported about six tons from such countries as Canada, Britain and Taiwan.
Most of the US plutonium went to America's European allies. But other countries received small amounts, including the Netherlands, Israel, Turkey, Iran, Iraq, Ireland, Uruguay, Venezuela, South Vietnam, Pakistan, South Korea, India, Colombia, Brazil, Argentina and Czechoslovakia.