Preparatory bodies play an important role in intergovernmental negotiation processes leading to the drafting of international treaties or the establishment of new institutions pertaining to the law of the sea. The paper offers some reflections on the evolution of the negotiations on an international legally binding instrument under the los Convention on the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction. The paper traces the genesis of the Preparatory Committee 2016–2017 and reviews its unique role in advancing the negotiation process towards the convening of an intergovernmental conference in 2018. Special mention is made of the role of European Union in edging the preparatory phase towards a successful outcome. The paper also touches on how the preparatory phase of a new marine biodiversity instrument differed in some significant respects from previous law of the sea negotiations.