About 8,000 men and boys were killed in 1995, in what has been described as Europe’s worst atrocity since World War II.
Foreign ministers are expected to attend the ceremony, joining massacre survivors and relatives of those killed.
The massacre, in the final two months of war that lasted 43 months, was a bid to ensure there were no Muslims to fight back or claim back Serb-occupied land or homes in the future.
Over 1,500 Bosnian Serb police backed by European Union troops were to enforce security, with tensions running high after two large bombs were last week discovered near the ceremony site, a cemetery in Potocari, just outside the town.
At the ceremony, the remains of 610 victims dug out from nameless pits and identified using DNA analysis will be given a Muslim burial.
However, around 5,000 body bags await analysis, and 20 more mass graves are yet to be exhumed.
A newly-opened grave will be uncovered during the ceremony, believed to contain at least 50 bodies.
Serbia’s President Boris Tadic said he will attend, along with a Serbian delegation.
The President of the International Criminal Tribunal for the former Yugoslavia (ICTY), American judge Theodor Meron and the EU Enlargement Commissioner Olli Rehn are also expected.
Bosnian Serb army commander General Ratko Mladic and the rebel state’s leader Radovan Karadzic have been indicted for genocide for the atrocity.
However both remain at large.
The United Nations war crimes tribunal has laid genocide charges against former Yugoslav president Slobodan Milosevic.
Many Serbians still believe the mass killings never took place, however a video last month surfaced showing the killing of Muslim civilians.