The Royal Festival Hall has received £950,000 from the Heritage Lottery Fund to restore and reinstall a grade I listed organ in its main auditorium.
The instrument, which has 7,710 pipes, was installed in the auditorium in 1954 but was removed for renovation work.
The restoration on the organ will be undertaken by Harrison and Harrison Ltd, its original creators.
The work, which is the final phase of revamp of the building on London's South Bank, will finish by 2013.
The organ was known for its open-plan design and eclectic tone. Most of the components of the organ are being stored in Durham.
It will be reinstalled in its original location at the heart of Sir Leslie Martin's concert auditorium in time for the instrument's 60th anniversary celebration in 2014.
Alan Bishop, chief executive of Southbank Centre in London, said: "I would like to thank the Heritage Lottery Fund for their significant contribution to the full restoration of the great organ of the Royal Festival Hall for the next generation."
He said a fundraising campaign would be launched in September to appeal for public support.
Sue Bowers, head of the Heritage Lottery Fund for London, said she was delighted that the restoration will put the "amazing internationally important organ back in its rightful place".