It is also seen as the most important since the end of apartheid.
There are more than 23 million registered voters in the country of 50 million people, and the Independent Electoral Commission (IEC) predicts that 80 per cent of them will cast their ballot.
The result is not in doubt. The ANC leader Zuma will be the next president of South Africa.
However, today’s ballot is the first major electoral test for the ruling party whose two-thirds majority is under threat from a breakaway party, Cope; the Democratic Alliance and a host of smaller parties.
Zuma was bullish ahead of voting. â€œWe expect that the people of this country will once again give the ANC a huge and decisive mandate,â€ he told reporters yesterday.
The snaking queues of thousands of people who had been prevented from voting under apartheid are likely to be repeated this year although the weeks-long wait for results has been reduced, with official figures expected from Saturday.
Former Nigerian President Olusegun Obasanjo jetted into the country on Monday morning to join a team of observers which would oversee the elections.
â€œOther people will say all elections are not without any problems. There (has been) no absolutely perfect election anywhere in the world so far,â€ he said.
Obasanjo, formerly a staunch ally of deposed South African President Thabo Mbeki, is part of a contingent of 2000 observers from home and abroad who will watch proceedings in the province to ensure that they are free and fair.
He toured the IEC’s special results centre in Durban and greeted and joked with observers from other organisations. He said he was not in the country as a judge, but merely to observe the process.
Obasanjo will lead an observer mission under the auspices of the African Centre for the Constructive Resolution of Disputes (Accord).
Accord has a mandate to mount an African election violence observer mission in conjunction with the Nairobi Peace Initiative and the West Africa Network for Peace. Together they form the African Alliance for Peace Initiative, under Obasanjo’s leadership.
â€œDemocracy should not be an exception in Africa, but normality. Elections are a period when people feel a sense of belonging to their country. Elections are an adequate reflection of the will of the people,â€ he said.
While in the country, Obasanjo would meet President Kgalema Motlanthe, ANC president Jacob Zuma, and his IFP counterpart Mangosuthu Buthelezi.
Serious competition at the polls has drawn an expensive response from the ANC, which has spent an estimated Â£34 millon in a campaign which has sought to emphasise the power and popularity of the party.
Markets in Africa’s biggest economies reflected increased fears that Zuma, who comes from the left wing of the party, may achieve a two-thirds mandate which would allow him to make changes to the constitution.
The contradictory pressures on the unpredictable president-in-waiting are reflected by his relationship with two key party figures: the country’s influential Finance Minister Trevor Manuel and the controversial ex-wife of Mandela, Winnie Madizekela Mandela.
The former is a fiscal conservative whose popularity with business leaders means he must be retained and the latter is a fiery populist with strong Communist party backing.Â Zuma is expected to find room for both of them in his post-election cabinet.
Senior figures from the business world have sought and received reassurances that Manuel will remain in his post. Reports that he was set to resign after the departure of the former president Mbeki last year were enough to send markets and the rand into a steep decline.
â€œThe one thing I know, and I have worked with Jacob Zuma for almost two decades, the one thing I know is that he will draw on highly skilled individuals,â€ the Finance Minister said yesterday. â€œHe wants to succeed. He is not going to set himself up for failure.â€
However, Zuma is expected to make some populist appointments with party sources mentioning Winnie Mandela for a possible senior post. The 72-year-old has spent much of the past decade in the political wilderness after convictions for theft and fraud while head of the ANC Women’s League.
She was earlier found guilty of kidnapping and held to be an accessory to the killing of a 14-year-old boy, Stompie Seipei, who was targeted by her own vigilante bodyguard, the Mandela United Football Club.
Despite these convictions and a past sacking for incompetence she remains extremely popular in the poorer townships and she still lives in the Orlando East area of Soweto.