The president and chief executive officer of South African petrochemicals group Sasol will not extend his contract beyond May next year and will move into an advisory role, the company said on Monday.
David Constable was appointed in 2011 and led Sasol's expansion plans in southern African and North America. Sasol did not provide reasons for Constable's decision.
Sasol's chairman Mandla Gantsho said in a statement the company's board of directors would identify and appoint an accomplished leader to replace Constable.
The company's shares had risen 0.22 per cent at 08.25 GMT.
The world's biggest maker of motor fuel from coal, said in March it could expand its $8.9 billion cracker project in the US and sell up to 400 megawatts of power that it generates in-house to South Africa's state-run power utility Eskom, which is struggling with power shortages.