Agnes Hallosserie leads the Biodiversity programme at Iddri. She is thus in charge of developing and implementing the biodiversity strategy of the organisation. She manages the programme’s team.
She worked at UNEP-WCMC (Cambridge, UK) on the integration of biodiversity issues in the climate policies of reducing emissions from deforestation (REDD+), with a focus on the forests of the Congo basin. She then joined the French Foundation for Research on Biodiversity in Paris (France) where she was head of the European and international coordination department. In this role, she engaged in the work of the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) and of the Convention on Biological Diversity (CBD), as advisor to the French delegation. She also worked for IPBES Executive Secretariat as Head of the technical support unit for the Assessment of the Sustainable Use of Wild Species. At the European level, she was involved in Biodiversa+ partnership, the main research planning and funding programme on biodiversity. She also led the executive secretariat of the Infrastructure Ecology Network Europe (IENE), dedicated to mainstreaming biodiversity in transport infrastructure. 
Agnes graduated from Pairs I Panthéon Sorbonne with a Master’s degree in international relations and action abroad. She dedicated her studies to sustainable development, which she also developed at the University of Oslo.