Millions of Egyptians have been heading to the polls since Saturday to endorse or reject amendments to the country’s constitution.
Citizens have been queuing to vote on Sunday, the second of three days of voting in a referendum that seeks to extend Sissi's presidency until 2030.
The changes to the constitution which for example will extend Sissi's current term to six years, and clear the way for his third term bid, were approved by the country's parliament earlier this week.
If Egyptians vote in favour of the changes, President Sisi will wield the powers to appoint the prosecutor general and top judges for the judicial system.
Until the constitutional amendments, Sissi was set to leave office at the end of his second term which should end in 2022.
The 64-year old came to power in 2013 following the military overthrow of Mohammed Morsi, a leading figure of the now banned Muslim Brotherhood.
As Egypt's sixth president, he won democratic elections in 2014.