The federal government is looking for a new secretary for the Department of Environment and Energy after Gordon de Brouwer quit "to pursue other interests".

Prime Minister Malcolm Turnbull made the surprise announcement on Tuesday, coming as the Coalition continues to grapple with the contested politics of energy costs, supply and introduction of Finkel Review recommendations including a proposed clean energy target.

Mr Turnbull said Dr de Brouwer, a former economics professor and three-decade public service veteran, would finish in his role on September 8.

The appointment of a new secretary is expected in due course.

A former Westpac, Australian National University and Reserve Bank staffer, Dr de Brouwer was reportedly considered for the top job at Treasury during the Abbott government.

"Dr de Brouwer has had an extensive and distinguished career with three decades of public service in academia and the public sector," Mr Turnbull said in a statement.

"Dr de Brouwer was a G20 sherpa and supported Australia's Prime Ministers at eight G20 summits. He was awarded a Public Service Medal and made a Knight in the Legion of Honour by the President of the French Republic for both his public and G20 service.

"As Secretary of the Department of the Environment and Energy, Dr de Brouwer oversaw the release of the Australian Antarctic Strategy and 20 year action plan as well as the Reef 2050 Long Term Sustainability Plan which was unanimously welcomed by the World Heritage Committee.

"Also during Dr de Brouwer's time as secretary, Australia signed and ratified the Paris Agreement on climate change."

Mr Turnbull thanked Dr de Brouwer for his advice and leadership throughout his career and for a commitment to the Australian Public Service.

"I wish him all the very best for the future," Mr Turnbull said.

Dr de Brouwer received the Public Service Medal in recognition of outstanding public service in the development of international economic policy, particularly in the formulation of the Australian Government's agenda to establish the G20.