President Salva Kiir has relieved Andrea Mayar and appointed Angelo Taban as the governor of Wau State.
Mr Mayar was removed after serving for one year in office. The circumstances surrounding the dismissal are unclear.
But the state has been witnessing small-scale insurgency and ethnic conflict between farming and livestock-rearing communities.
Tens of thousands of denizens – mostly women and children – have been sheltering at churches and UN camp.
The presidential press secretary, Ateny Wek Ateny, says the decree was among several others that were issued by President Kiir last evening.
Kiir also relieved Deng Mading Majak, the Chairperson of the Abyei Joint of Oversight Committee and replaced him with Deng Arop Kuol.
The Chairperson of Public Grievances and Employees Justice, Deng Biong Majak, has also been removed from office and replaced with Biong Deng Kuol.