Chadian army has been on the front line of a regional military operation against Boko Haram as attacks spread.
Chadians voted on Sunday in a presidential election as the incumbent, Idriss Deby, sought a fifth term in office.
President Deby, who took power in a military coup 26 years ago, faces 12 challengers but is widely expected to win another term.
“I call on Chadians to vote in calm and serenity. Our country is starting from a long way back but the future looks bright. I ask all politicians to respect the verdict of the ballot box,” Deby told journalists as he voted.
Witnesses said thousands of voters cast their ballots at polling stations in the capital, N’Djamena, in the first election the central African country has held using biometric data.
“We came to vote for the president to guarantee peace in our country. Around us in the neighbouring countries there are too many problems,” civil servant Fatima Zara told Reuters news agency.
Polling stations closed at 6pm (1700 GMT) and vote counting began, watched in some places by small crowds.
Results are not expected for two weeks, according to a timetable set out by the electoral commission.
In recent weeks, protest marches have been banned and government opponents imprisoned. The opposition, which is fractured, boycotted the last election in 2011.
On the campaign trail, Deby, 63, has hammered home a vow to promote the “emergence” of Chad, where seven out of 10 people cannot read or write, and half the population of 13 million live below the poverty line despite new oil revenues.
Oil production started in 2003 and now accounts for 60 percent of export earnings. But Chad ranks fourth from last in the UN Human Development Index, and more than one child in 10 dies before the age of five, according to World Bank estimates.
Chad also faces significant security threats with two attacks in the capital last year.
Deby has tightened security to address those threats while maintaining a strong presence in a regional force fighting the Nigeria-based Boko Haram group.