The Institute of Electrochemistry and Energy Systems (IEES) at Bulgarian Academy of Sciences (BAS) is one of the main chemical institutes of the Bulgarian Academy of Sciences and a leading scientific organization in the country in the field of electrochemical power sources and energy storage systems. IEES conducts fundamental scientific research in the fields of electrochemical power sources, hydrogen energy systems, electrochemical methods and electrochemical material science. Innovative applied researches are focused on electrochemical conversion and energy storage, creation of new instrumental techniques and technologies. The activities at IEES extend from development of new materials through the creation and testing of components to the elaboration of laboratory prototypes and semi-industrial pre-market systems. In the institute are being trained specialists, PhD students and post-doctoral students.

The IEES executes projects funded by the National Fund for Scientific Research, the National Innovation Fund, European Framework Programs, NATO, UNESCO, the Global Consortium for Lead Acid Batteries (ALABC) and other international organizations; cooperates with companies from the country and abroad and performs specific assigned tasks in the applied sciences field. From 2018 IEES is coordinator of the Scientific Infrastructure "Energy Storage and Hydrogen Energetics" (SI ESHE) and is a partner in the Centre of Excellence "National Centre of Mechatronics and Clean Technologies". In March 2019, the implementation of the „Center of Competence HITMOBIL” project was launched, where the institute is a leading organization.