Southern Sudanese are set for the referendum to decide whether they want to secede from the north or remain united.
The week-long polling will start on Sunday across Sudan and eight other countries with substantial southern Sudanese diasporas.
In an appeal to his people, Silva Kiir, the president of southern Sudan, urged them to behave in a peaceful and responsible manner during the referendum.
"This is a most important and decisive moment in your life. It is not the end of a journey, but the beginning of a new journey,” Kiir said, referring to the Comprehensive Peace Agreement [CPA] signed by the north and the south that brought an end to the Sudanese civil war in 2005 and made the referendum possible.
"Today there is no return to war. There is no substitute for peaceful co-existence and it is critical for the coming generation," he said.
In Juba to see first-hand that the referendum passes off without any incident was Senator John Kerry of the US alongside 1,400 international observers spread across Sudan.
"The people of southern Sudan have reached this stage after going through a series of hardships imposed on them by slavery, colonialism and internal turmoil. Tomorrow, they get the right to determine their own future," Kerry said.
About 6,000 security personnel will protect the polling stations in south Sudan
