In Tanzania, the official visit will be part of the celebrations of the 50th anniversary of independence from the UK..They will visit a Masai village, a national park and Zanzibar.They will meet President Jakaya Kitwete at his residence in the country's capital, Dar es Salaam.
The duchess will make visits to child literacy programmes in both countries.
During the tour of South Africa they will visit Cape Town, Johannesburg, Pretoria and KwaZulu-Natal, and they are likely to be guests of the acting head of state as President Jacob Zuma has other engagements around the world
Prince Charles has recently become president of World Wildlife Fund (WWF) in the UK, and in both Commonwealth countries there will be a strong focus on the charity's work to protect endangered species and fragile ecosystems.