Former Ivory Coast President Laurent Gbagbo has arrived at the International Criminal Court (ICC) at The Hague after being flown from Ivory Coast.
He faces four charges of crimes against humanity - murder, rape and other forms of sexual violence, persecution and "other inhuman acts".
The charges were allegedly committed between 16 December 2010 and 12 April 2011.
The ICC has been investigating unrest after last year's disputed elections.
The transfer comes just two weeks before legislative elections.
Laurent Gbagbo had been under house arrest in Korhogo in the north of Ivory Coast since April when he was ousted.
He will be the first former head of state to be tried by the ICC since it was set up in 2002.
The ICC opened an investigation last month into killings, rapes and other abuses committed during the four-month conflict in Ivory Coast which began when Mr Gbagbo refused to give up power to Alassane Ouattara in a presidential election last year.
ICC chief prosecutor Luis Moreno-Ocampo visited the country in mid-October to investigate the post-election violence.
He said his investigation would be impartial, and that he would focus on up to six people who he said were most to blame for the violence.
A statement read on Ivorian national television signed by the state prosecutor, Simplice Kouadio, said the ICC had issued an arrest warrant for Mr Gbagbo last week, which he had received this Tuesday in the presence of his lawyers.
Human rights groups welcomed the arrest warrant, but also cautioned against "victor's justice".
"While the Gbagbo camp fuelled the violence, forces on both sides have been repeatedly implicated in grave crimes," said Elise Keppler of Human Rights Watch.
"Victims of abuse meted out by forces loyal to President Ouattara [also] deserve to see justice done," she said.
In a statement to Reuters, an adviser to Mr Gbagbo, Toussaint Alain, branded the former president's transfer "victor's justice".
But Mr Moreno-Ocampo vowed Mr Gbagbo would not be the last person to be brought to account, saying: "Ivorian victims will see justice for massive crimes: Mr Gbagbo is first to be brought to account, there is more to come."
Although Ivory Coast is not one of the member countries covered by the ICC, it has accepted its jurisdiction.
Mr Gbagbo is also being investigated by Ivorian justice officials for "economic crimes". He has been charged with looting, armed robbery and embezzlement.
Laurent Gbagbo was the president of Ivory Coast for 10 years, during which time the country was virtually partitioned by civil war.
But it is the period since the presidential elections a year ago that the prosecutors of the ICC have been investigating.
Mr Gbagbo refused to give up power when his rival Alassane Ouattara was internationally recognised as the winner of last November's presidential vote.
About 3,000 people died in the post-election violence provoked by Mr Gbagbo's decision to cling to power.
The BBC's World Affairs correspondent Peter Biles says Mr Gbagbo's transfer to The Hague will be welcomed by some, but it could also re-open the wounds in a country still traumatised by conflict.