Eskom announced on Monday that its Group Treasurer, Andre Pillay, had tendered his resignation.
He will leave the power utility at the end of August 2019. He had served in the position since 2016.
Eskom said Pillay's contribution to the successful execution of Eskom's Treasury mandate had been "immeasurable".
The power utility did not say why Pillay had chosen to step down. His replacement will be announced "in due course".
Pillay's resignation comes seven weeks after Eskom's CEO Phakamani Hadebe announced his resignation. Hadebe will leave Eskom at the end of the month.
Calib Cassim, Eskom’s chief financial officer, said Eskom asked Pillay to remain in the position for the next two months to "ensure a seamless transition and business continuity through the handover process".
"We believe that Treasury operations will continue with ease with the support of the current Treasury leadership”, he said.
President Cyril Ramaphosa, in his State of the Nation address in mid-June, announced that government would expedite a portion of the R230bn that Eskom is set to receive in government support over ten years.
Finance Minister Tito Mboweni, meanwhile, will on July 23 introduce a special spending bill in Parliament which will give further details on government support for Eskom.