By Martin Plaut
Africa editor, BBC News
The Mo Ibrahim Prize - the world's richest - is being presented in London to a former African head of state for the excellence of their leadership.
Joaquim Chissano is a frontrunner for the prize
The prize is worth $5m (£2.5m) over 10 years, and then $200,000 a year.
Mobile phone millionaire Mo Ibrahim is funding the project in the hope it will help improve governments' performance.
Among 13 leaders under consideration by a panel are former Tanzania leader Benjamin Mkapa and Joaquim Chissano, who brought peace to Mozambique.
The winner of the prize will have been selected by a panel chaired by former UN Secretary General Kofi Annan.
The committee - which also includes the former Irish President, Mary Robinson, Finnish President Martti Ahtisaari and head of the Organisation of African Unity, Salim Ahmed Salim - will have assessed and reflected on the relative merits of 13 African former heads of state, all of whom left power in the past three years.
The prize is the brain-child of the mobile-phone millionaire, Mo Ibrahim, who is funding the project in the hope it will improve the performance of African governments.
Ibrahim hopes the prize will increase Africa's self-dependence
The Sudanese businessman hopes it will bring a day when the continent's people no longer need to live on aid.
"We need to remove corruption, we need to improve governance, we need to be healthy and then we don't need the aid," said Mr Ibrahim.
"The day we don't need any aid, that is the most wonderful day of my life."
Among the eligible leaders are a fair number no self-respecting panel would seriously consider - men who hung onto power decade after decade, giving Africa nothing but a bad name.
At least six first took power by staging coups.
Some had to be pried from their posts.
One - Somalia's Abdiqasim Salad Hassan - had no state to administer.
But there are some very capable leaders among them.
Benjamin Mkapa went a long way to bringing prosperity to Tanzania.
Albert Rene of Seychelles may have had his flaws, but he presided over a thriving island state.
And Domitien Ndayizeye did much to reconcile Burundi's Hutus and Tutsis.
But perhaps the most shining example is Joaquim Chissano, who brought Mozambique from a murderous civil war to peace and progress during his 19 years in office.