The central objective of this Paper is to develop an analysis of the position occupied by civil society organizations in International Human Rights Law, specifically in human rights protection at the international level. In this regard, the proposed examination will focus on the discussion regarding the accountability of said organizations, at this level.  Introducing, from a historical perspective, the form of interaction of these actors with supranational organizations, it is possible to draw conclusions regarding its legitimacy and its accountability or lack thereof. By drawing on the concept of legitimacy as used in the international sphere, to which the idea of accountability is directly linked, it can be developed certain analytical tools that permit the identification of specific aspects of accountability that are fundamental in understanding the mode of operation of civil society organizations in International Human Rights Law. As a practical example, it is studied the case of the INGO Accountability Charter, currently known as Accountable Now.     Recebido em: agosto/2018.Aprovado em: dezembro/2018.