Mo Ibrahim is a Sudanese-born telecoms entrepreneur
Nearly two-thirds of sub-Saharan African countries have improved their governance, according to a new index.
The Ibrahim index, based on data from 2006, listed Mauritius as the best-governed out of 48 countries Liberia as the most improved.
Somalia is ranked last, a place behind the Democratic Republic of Congo.
The index is funded by Mo Ibrahim, an entrepreneur and philanthropist who has also set up a $5m annual prize for retired African leaders.
The BBC's East Africa correspondent Peter Greste says the bottom and top-ranked countries are no great surprise, but there does seem to be an unexpected rise in the standards of governance and the category with the biggest improvement - human rights.
Mr Ibrahim said 31 out of 48 countries had recorded improvements in areas like safety and security, human rights, and the rule of law.
3: Cape Verde
5: South Africa
47: DR Congo
"Obscured by many of the headlines of the past few months, the real story coming out of Africa is that governance performance across a large majority of African countries is improving," the Sudanese-born telecoms entrepreneur said.
"I hope these results will be used as a tool by African civil society to hold their governments to account."
Liberia, ranked in 38th place, was singled out as the most-improved country.
The index also recorded that 33 African countries had shown improvements in macroeconomic stability and financial integrity.
"Africa is open for business," Mr Ibrahim told Reuters news agency.
"Investors should look at our growth. And with the global financial situation the way it is, perhaps their money is safer in Africa than in the US."
Mary Robinson, a former UN High Commissioner for Human Rights and member of the Mo Ibrahim prize committee, said there had been improvements in rights and participation across the continent.
"More sub-Saharan African countries than ever are holding democratic elections, and I am hopeful that this will help form the platform for continued progress across the continent," she said.
Last year, former Mozambique President Joaquim Chissano won the first Mo Ibrahim prize awarded to a retired African leader for excellence in leadership.