This chapter examines the authority to grant provisional measures. Section 2 considers the nature of the arbitral tribunal’s authority to grant provisional measures and analyzes the inherent power of international courts or tribunals to take interim measures in the international judicial practice, as well as the sources of this inherent power. Section 3 discusses the exercise of the authority to grant provisional measures and analyses the emergent exercise of the power, the discretionary exercise of the power and the right of the parties to present the case. Section 4 analyzes the distribution of the power to take interim measures between the arbitral tribunal and the domestic court in terms of pre-award security in ICSID arbitration and non-ICSID arbitration.