Aides said an autopsy showed he died of kidney failure. He was 82.
Oginga Odinga was one of the last survivors of the generation who led the fight for African independence, but he remained an active politician until the end, even though he was almost completely blind and enfeebled. In African politics age, even hampered by frailty, is more revered than youth.
He was Kenya's first vice-president, but fell out with President Jomo Kenyatta and was sacked and then detained. He entitled his autobiography Not Yet Uhuru, playing on the word for freedom in Swahili. For this he was perceived as a radical by the British, but he always denied he was a Communist. When he died, Mr Odinga was the official leader of the opposition in parliament and led one of the factions of the opposition movement, Ford, the Forum for the Restoration of Democracy. But his power base was the Luo people, one of the largest ethnic groups in Kenya.
In the 1960s it was the forging of an alliance between the Luo, led by Odinga, and the Kikuyu, led by Jomo Kenyatta, that outmanoeuvred the colonial authorities and brought about the timing and manner of Kenyan independence.
The reforging of that alliance in 1990 under the Ford banner brought together Ken Matiba, the powerful Kikuyu leader, and Mr Odinga and forced President Daniel arap Moi to accept multi-party democracy and an election.
But the alliance did not hold. Personality clashes, personal ambition and tribal sentiment led to the break-up of the alliance and Ford split into two, Odinga leading the largely-Luo Ford Kenya. The split cost the opposition victory and Odinga lost his last chance to fulfil a lifelong ambition to be Kenya's leader.
Unwilling to remain in opposition, he held secret talks with Mr Moi last year and toned down his language. He also admitted he had accepted money that had been stolen from the state in a scam known as the Goldenberg scandal. This caused a further break-up of Ford-Kenya when many of its 'young turks' walked out. The question now is whether the new leader of the Luo can work with the emerging opposition politicians from other groups.