Voting had ended at 9pm on Monday, but commission head Abdel Aziz Abdel Aziz Salman said in a statement on Monday night that Egyptians would have an extra hour to choose either leftist politician Hamdeen Sabahi or former army chief Abdel Fattah Al Sisi as the country's head of state.
Reports suggested late on Monday that the turnout had been relatively low, with a handful of prominent television anchors urging people to vote en masse on Tuesday.
Egypt's Prime Minister Ibrahim Mahlab also announced late on Monday that Tuesday would be a holiday for employees in the government sector, in order to allow Egyptians to vote.
Mahlab also called on private businesses to grant their employees a holiday so they can cast their ballots.