Marina Litvinenko said it was a "special" day and she is confident the inquiry into her husband's death will get under way in January, as directed by its chairman Sir Robert Owen.
At a hearing at the Royal Courts of Justice yesterday, Sir Robert formally suspended an inquest into Mr Litvinenko's death and opened a public inquiry, which was announced last week by Home Secretary Theresa May.
He praised Mrs Litvinenko for her patience in the face of "highly regrettable" delays and said the inquiry's substantive hearings will begin in January 2015. Mr Litvinenko, who fled to Britain in 2000, died after drinking tea laced with radioactive polonium-210 while meeting two Russian men - one a former KGB officer, at the Millennium Hotel in London's Grosvenor Square. His family believes he was working for MI6 at the time and was killed on the orders of the Kremlin.
Former KGB bodyguard Andrei Lugovoi and Dmitri Kovtun have been identified as the prime suspects in the killing, but deny involvement and remain in Russia.
Mrs Litvinenko said she was confident the inquiry will start on schedule, adding: "Everybody all around the world will know the truth."
Opening the inquiry, Sir Robert told the hearing that alleged Russian state responsibility in the 43-year-old's death was of "central importance". Britain's responsibility for protecting the former KGB officer will not be investigated as there is no evidence to suggest failings on the state's part, he told the court. But he added, if evidence was discovered to suggest Britain could have prevented his death, he was able to bring in the issue.
He adjourned the inquiry until September 5 when a preliminary hearing will take place, and said its substantive hearings "must begin in January 2015".