All its previous elections have led to either disputes and claims of rigging, outbreaks of deadly violence, or both. So Kenyans are hoping that this time will be different.
Who are the candidates?
The four-time failed presidential candidate Raila Odinga is trying his luck again. The 77-year-old former prime minister has a reputation as a formidable campaigner.
His big rival is the 55-year-old Deputy President William Ruto. He has proved a match for Mr Odinga on the campaign trail and has drawn large crowds.
There are two other lesser-known names on the ballot paper.
George Wajackoyah has caught the attention with his proposal to legalise marijuana cultivation and the export of snake venom. David Mwaure Waihiga is running on an anti-corruption message.
Why isn’t the president backing his deputy?
Things have got topsy-turvy in Kenyan politics. Mr Odinga was once an implacable foe of the incumbent, President Uhuru Kenyatta. The enmity between them can be traced back 60 years when their fathers, both independence leaders, fell out.
But in a remarkable turnaround the two men shook hands and made up in 2018 and Mr Kenyatta has thrown his weight behind Mr Odinga’s campaign.
This left Mr Ruto out in the cold and made for several years of an uncomfortable relationship at the top.
What is the main issue?
Arguably, the deputy president has defined the grounds that this election is being fought on – the economy.
Whereas in recent elections debates about corruption and justice have dominated, this time people are very much thinking about their pockets.
Coming from a modest background, Mr Ruto, who is now a wealthy man, has styled himself as the champion of the poor. In this young nation, he has focussed on policies to tackle youth unemployment and in 2018 coined the phrase “hustler nation” to refer to people struggling to make ends meet.
In an imaginative act of political symbolism, alongside the usual election merchandise, he has handed out free wheelbarrows at his campaign rallies.
He has also presented his candidacy as an attempt to end the domination of Kenyan politics by dynastic families: the Kenyattas and Odingas.
Mr Odinga is promising to continue the president’s development agenda and improve the lives of vulnerable Kenyans by giving them a 6,000 Kenyan shilling ($50; £40) monthly stipend from a new social protection fund if he is elected president.
He has also pledged to provide affordable healthcare through what he calls “Baba Care”, promoting himself as a fatherly figure in a nation of more than 56 million.
Is there an ethnic dimension to this election?
In Kenya, many votes are cast along ethnic lines and in previous years, this has sometimes spilled over into nationwide violence with people being attacked and killed merely on the basis of which community they come from.
The disputed poll of December 2007 was followed by weeks of ethnic-based violence in which 1,200 people died and more than 500,000 fled their homes.
Since then, politicians have been keen to emphasise peaceful democratic engagement. But the issue of ethnic affiliation has not gone away.
Mr Odinga, a Luo, and Mr Ruto, a Kalenjin, will both be relying on the votes of their large ethnic groups to propel them into State House.
But in a calculated move both have chosen running mates from the country’s largest ethnic group – the Kikuyu. In Martha Karua, Mr Odinga has also picked the first woman to run on a major political party’s presidential ticket.
Concerns remain that in parts of the country ethnic tensions could spill over into violence and some people are moving to areas where their ethnic groups forms the majority to avoid being targeted. But, in light of what happened after the 2007 vote, the authorities have been taking steps to make sure that things are peaceful.
Will it be free and fair?
People will also be watching to see if the electoral commission has straightened out the problems which in 2017 led to the annulment of the initial election result and the whole thing being re-run.
The issue then was that the system to electronically transmit results from every polling station was not working in some places. Opposition lawyers representing Mr Odinga argued successfully that this allowed the vote tallies to be tampered with.
This time the authorities say they have taken measures to make sure that electronic transmission will proceed smoothly.
The speed of getting the election result will depend on how well that system works, but come the night of 9 August every result will be closely scrutinised by the candidates’ representatives to make sure that they are not cheated out of the top job.
Are other elections happening?
On polling day, Kenyans will be casting multiple votes.
Alongside the presidential election, people will be voting for MPs and senators to go to the national parliament, county governors and county assembly members.
And women get an extra vote to elect one of 47 women’s representatives to sit in the national assembly.
How will the election work?
Polls are due to open for 12 hours from 06:00 local time (03:00 GMT). Anyone still in the queue at closing time will be allowed to vote.
Once closed, officials will start counting the votes at each polling station.
It is not yet clear when the presidential election result will be announced but the electoral commission has a maximum of seven days to count and tally the votes.
To win, a candidate needs more than half the votes cast nationally and at least 25% of the votes cast in each of more than half of the counties.
If that threshold is not reached then the election goes into a second-round run-off between the top two candidates.
