World leaders on Monday said Kenya had lost a courageous woman.
South African Nobel laureates Nelson Mandela and Desmond Tutu hailed the legacy of Kenyan environmental activist Wangari Maathai, calling her a "true African heroine".
"She understood and acted on the inextricable links between poverty, rights and environmental sustainability. One can but marvel at her foresight and the scope of her success. She was a true African heroine," Tutu's office said in a statement.
"Our condolences go to Professor Maathai's family, to the people of Kenya, and to the countless women (and men) across Africa and the world to whom she was an inspiration," it said.
The Nelson Mandela Foundation, responsible for carrying on the work of South Africa's first black president, hailed her as "exceptional environmental activist".
Former UN Secretary General Kofi Annan said as the first African woman to be bestowed with the award, Prof Maathai would forever be celebrated and honoured.
“Wangari Maathai will be remembered as a committed champion of the environment, sustainable development, women’s rights, and democracy.
“Her energy and life-long dedication to improve the lives and livelihoods of people will continue to inspire generations of young people around the world,” he said in a statement.
President Kibaki said the Nobel Laureate was a global icon and a great human rights crusader.
"In politics, she will be remembered for the role she played in agitating for political reforms that paved the way for the country’s second liberation, " he said.
Prime Minister Raila Odinga termed Prof Maathai as a heroine of Kenya's national struggles easily recognised locally and abroad.
"We all knew her as a voice of reason, a lady who stood above our artificial divisions of race, tribe and region and championed the cause of humanity," he said.
Speaker of the National Assembly Kenneth Marende said Kenya had lost one of its greatest icons.
"I had an opportunity to serve with her in the 9th Parliament. She was kindhearted, helpful and committed to serving her country the best way she could. We have lost a true hero," he said.
UNEP Executive Director Achim Steiner also paid tribute to Prof Maathai and said she was the inspiration behind UNEP’s Billion Tree Campaign, which was launched in 2006.