After studying electrical engineering and fuel engineering at the Technical University of Aachen and obtaining his doctorate, Dr.-Ing. Wolfgang Cieslik (born in 1952) began his professional career in 1984 at Ruhrkohle Aktiengesellschaft. For twenty years he worked there in various positions, including Chairman of the Management Board of Ruhrkohle Verkauf GmbH. In 2004 he moved to the Management Board of RAG subsidiary STEAG AG (later STEAG GmbH) and additionally became Chairman of Saar Energie AG and RAG Trading GmbH. In 2007 Wolfgang Cieslik became a member of the Management Board of Evonik Steag GmbH, which changed its name to STEAG GmbH in 2011.

On the Management Board, Wolfgang Cieslik is responsible for Fuel Procurement and Electricity Marketing as well as the By-products and New Energies divisions.