The law of international organisations needs to address comprehensively, the legal question of the accountability of such Organisations. In the contemporary world, whereas states, multinational corporations, and individuals can be held accountable under applicable systems of law, there is no equivalent set of rules that applies to international organisations. The OPCW, a global disarmament Organisation, is a good model of an accountable Organisation. The Chemical Weapons Convention embodies various sets of rules and provisions, which ensure the accountable functioning of the Organisation. This article examines the concept of the accountability of international organisations as envisioned by the International Law Association, and analyses the concept in the context of the OPCW.