War crimes suspect Goran Hadzic has been flown from Serbia to face the UN court at The Hague.
A police motorcade, sirens blaring, was earlier seen leaving the Belgrade jail where Mr Hadzic was being held.
Before being taken to the airport, Mr Hadzic, 52, was allowed to see his sick mother in northern Serbia.
Mr Hadzic led Serb separatist forces during Croatia's 1991-1995 war and was arrested on Wednesday after seven years on the run.
The plane carrying Mr Hadzic has now landed in Rotterdam.
Mr Hadzic was a central figure in the self-proclaimed Serb republic of Krajina in 1992-1993, leading the campaign to block Croatia's independence from Yugoslavia.
He faces 14 counts of war crimes and crimes against humanity, including persecution, extermination and torture.
He is held responsible for the massacre of almost 300 men in Vukovar in 1991 by Croatian Serb troops and for the deportation of 20,000 people from the town after it was captured.
After the war, Mr Hadzic lived openly in the northern Serbian city of Novi Sad until 2004, when the Hague War Crimes Tribunal indicted him and he disappeared.
Mr Hadzic is the last fugitive of 161 indicted for war crimes during the break-up of the former Yugoslavia.
Serbian Justice Minister Snezana Malovic said she had signed the order for Mr Hadzic's extradition on Friday, Associated Press reported.
BBC correspondent Mark Lowen in Belgrade says Mr Hadzic's extradition is a defining moment for Serbia.
He says the country hopes it will allow it to draw a line under the war crimes story and move closer to European Union membership.
For years prosecutors in The Hague complained that Belgrade was not doing enough to track down top war crimes suspects, including Mr Hadzic. That criticism delayed progress in Serbia's EU bid.
His arrest comes less than two months after Serbia caught former Bosnian Serb military commander Ratko Mladic.
Serbian President Boris Tadic told reporters on Wednesday that Mr Hadzic had been detained in the mountainous Fruska Gora region, north of Belgrade, near his family home.
Serbian prosecutor Vladimir Vukcevic said the breakthrough in the hunt for Mr Hadzic came when he tried to sell a stolen painting by Italian artist Amedeo Modigliani.