The dismissal of the finance minister, Bak Barnaba Chol, was announced in a decree read on state TV late on Friday.
As South Sudan’s economic crisis continues, some civil servants have gone at least six months without being paid salaries.
Over the past two months the local currency, the South Sudanese pound, has lost about half of its value against the dollar, fueling a surge in prices of food and other essential goods.
Chol, 43, an ally of Kiir, was appointed as finance minister last August and had undertaken various reforms including trying to clean the government employee register to get rid of “ghost staff.” He also tried to plug revenue leakages.
Kiir appointed Awow Daniel Chuong, a former minister for petroleum, to replace Chol.