Mr. Mbeki, who has made the advancement of women a cornerstone of his administration, made it clear that gender was an element in his choice of deputy this time around.
"We thought that this gave us an opportunity further to strengthen the participation of women in the executive and that is part of what influenced the decisions that we took," he said.
But gender was unlikely the only consideration in Ms. Mlambo-Ngucka's promotion. She comes to the post with a formidable reputation as an efficient and tough minister, while at the same time being a strong team player and skillful negotiator.
Her appointment has been warmly welcomed by business leaders with whom she developed good relations while shepherding the mining sector through major legislative changes designed to ensure equal participation in the industry by all races.
The chief executive of Business Unity South Africa, said Mr. Mbeki was rewarding Ms. Mlambo-Ngucka for her competence and innovation. And the South African Chamber of Business with whom she had a rocky relationship in the early days of her ministry describes her as very strong and someone who will be a good counterpart for Mr. Mbeki.
But some opposition parties say that Mr. Mbeki may have taken a risk in appointing Ms. Mlambo-Ngucka as her brother's company had business dealings with a firm that is currently implicated in a potential scandal.
The Institute for Democracy in South Africa (IDASA) urged South Africans to allow the new deputy president an opportunity to prove herself before commenting.
Ms. Mlambo-Ngucka is married to the former national director of public prosecutions who launched the investigation that led to her predecessor, Jacob Zuma, being fired from his post last week.
Mr. Mbeki appointed another woman, Deputy Trade and Industry Minister Lindiwe Hendricks to succeed Ms. Mlambo-Ngucka. He appointed two new deputies to trade and industry, one male and one female.