Nineteen candidates are hoping to replace the incumbent, former football star George Weah, who is seeking a second term.
The two main challengers are former Vice-President Joseph Boakai and the businessman Alexander Cummings.
Both were in an alliance of opposition parties but the coalition broke up after disagreements over who should run for president.
Despite some progress in terms of education and the supply of electricity, critics say there has been widespread corruption during Mr Weah’s time in power.
He is pledging to build new roads, a timely subject during elections in the rainy season when large parts of Liberia’s network are cut off from the capital, Monrovia.
Mr Weah came to power in 2017 on a wave of popular support after two previous unsuccessful attempts.