Al Jazeera's Harry Smith, reporting from The Hague, said: "This is the day everyone connected with the international tribunal has been waiting for.
"It is the day many victims of the crimes in the former Yugoslavia have been wating for.
"The one person who is probably not looking forward to the events of the day is Radovan Karadzic himself."
Smith said it was not clear how long the hearing would last.
"It could last 10 minutes; it could go on for more than an hour. A lot depends on what Karadzic himself decides to do. We know that he intends to defend himself. That could mean delays as it did in the case of Milosevic [ex-Serbian president].
"The prosecutors are very eager to try and avoid that sort of disruption. Quite what they intend to do we don't know. But they say they have learnt a lot from the case of Milosevic."
Shorn of beard
Since his arrest in Belgrade Karadzic has been shorn of the beard and the long hair that helped disguise him as an alternative healer in the years following the war.
He was flown to the Netherlands on Wednesday morning.
Similar to Slobodan Milosevic, the former Serbian president, Karadzic has suggested he wishes to defend himself, a move which could protract the proceedings.
Serge Brammertz, the chief prosecutor, said he would conduct the trial efficiently, learning from the Milosevic case.
"Of course it will take some months before the prosecution and defence will be ready to start. It will be a complex trial but we are fully aware of the importance of being efficient," he told reporters on Wednesday.
Brammertz called the arrest a "major achievement".
During proceedings before Judge Alphons Orie, he will be asked to enter a plea to the charges against him after the indictment or a summary of the indictment is read.
Karadzic's lawyer in Belgrade has said the 63-year-old believes he will be cleared of genocide.
Earlier this week relatives said Karadzic was in good spirits and preparing his defence.
Karadzic's delivery to The Hague was key to Serbia securing closer ties with the European Union and his arrest was seen as a pro-Western signal by the new government sworn in this month.
France, which holds the EU presidency, said in a statement that Karadzic's arrest and transfer "mark an important step in the process of reconciliation in the western Balkans and in the rapprochement between Serbia and Europe".