October 1 - Iran meets six world powers in Geneva. Iran accepts a plan at the talks to send 75 percent of its low-enriched uranium (LEU) to Russia and France. There it would be made into special fuel for a Tehran reactor making medical materials.
October 21 - IAEA presents draft deal to reduce Iran's stockpile of enriched uranium.
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October 25 - U.N. nuclear experts inspect the newly disclosed centrifuge plant being built near the Shi'ite holy city of Qom. The site will refine uranium for civilian nuclear energy.
October 30 - Iran tells IAEA it wants fresh nuclear fuel for a reactor in Tehran before it will agree to ship some enriched uranium stocks to Russia and France, according to the U.N.
November 18 - Iran says that Tehran will not send its enriched uranium abroad for further processing but would consider swapping it for nuclear fuel within its borders.
November 19 - U.S. President Barack Obama issues a strong warning to Iran of the consequences of its failure to respond to the nuclear deal.
November 24 - World powers have drafted an IAEA resolution urging Iran to clarify the purpose of its previously secret uranium enrichment site, diplomats say.
November 26 - Outgoing U.N. nuclear watchdog chief Mohamed ElBaradei criticizes Iran's blockage of a plan to divest it of possible nuclear bomb material as "disappointing."
November 27 - The IAEA votes to censure Iran for developing the Fordow uranium enrichment plant near Qom in secret and demands Iran freezes the project.
November 29 - Iran announces plans to build 10 more nuclear sites in a swipe at growing pressure to rein in its atomic work.
January 19, 2010 - Diplomats say Iran has formally rejected key parts of the deal to send abroad for processing most of its material that could be used to make nuclear arms.
February 2 - President Mahmoud Ahmadinejad announces Iran is ready to send its enriched uranium abroad in what appears to be an easing of its position. The next day it launches a Kavoshgar-3 rocket capable of carrying a satellite, a move Washington describes as a "provocative act."
February 9 - Iran begins making higher-grade nuclear fuel, enriched to a level of 20 percent, at its Natanz facility.
February 18 - In unusually blunt language, an IAEA report, for the first time, suggests Iran is actively pursuing nuclear weapons capability.
March 18 - U.S. Secretary of State Hillary Clinton, visiting Russia, criticizes Russia's plans to start up a nuclear power station in Iran, describing them as premature given uncertainty about Tehran's nuclear ambitions. -- Russian Prime Minister Vladimir Putin announced the same day that Russia would start up the reactor at the Bushehr plant in the summer of 2010.
April 9 - Ahmadinejad showcases an improved centrifuge which officials say will enrich uranium faster than existing models. He also says Iran's nuclear path is irreversible.
April 12 - Obama's drive for tougher sanctions on Iran gains momentum at the start of an unprecedented two-day summit of nearly 50 countries that Obama has called to highlight the global threat of nuclear terrorism.
April 19 - Iran says it will start work on a new uranium enrichment plant as part of a big expansion of its nuclear programme announced last November.
April 27 - Brazil has offered to mediate to help end the West's standoff with Iran over its nuclear programme, Foreign Minister Celso Amorim says.
-- He said Brazil could work with Turkey, which has already offered to help, and act as an honest broker. May 12 - U.N. resolutions aimed at increasing sanctions against Iran over its nuclear programme "are not worth a penny" and Tehran will give no ground to pressure, Ahmadinejad says. The remarks come as the six powers continue to work on a new draft sanctions resolution, meeting in New York.
May 17 - Iran, Brazil and Turkey sign a nuclear fuel swap agreement. Iran says it has agreed to transfer 1.2 tonnes (2,646 lb) of its low-enriched uranium to Turkey within a month in return for higher-enriched nuclear fuel for a medical research reactor.
May 18 - The U.S. hands the U.N. Security Council a draft resolution that will expand U.N. sanctions against Iran by hitting its banking and other industries.
May 19 - The draft resolution against Iran has no legitimacy, the Fars news agency says, quoting an Ahmadinejad ally.
May 31 - A new IAEA report shows Iran's low-enriched uranium stockpile has grown to 2.4 tonnes, so that even if the 1.2 tonnes was shipped out now it would still leave Iran enough material for a nuclear weapon if enriched to higher levels.
June 2 - Iran is enriching nuclear material to higher levels as a backup plan as it fears it will not receive foreign fuel for a medical research reactor, Tehran's envoy to the IAEA says.
June 9 - The U.N. votes to extend sanctions against Iran.
IN PICTURES: Who has nukes?