Venezuela's National Electoral Council had earlier extended voting until 8 p.m. from the original closing time of 4 p.m.
In the past, Venezuelan polling stations have usually stayed open until 6 p.m.
Preliminary results could be released a few hours after the booths are closed if a clear tendency in the vote is apparent.
Huge lines of voters formed at ballot centers throughout Venezuela to answer the referendum question on whether they wanted to end the mandate of the populist president, whose rule has sparked an ongoing and often violent political conflict in the world's No. 5 oil exporter.
CARACAS, Venezuela (Reuters)