This report provides an examination of the rules on provisional measures under Article 290 of the United Nations Convention on the Law of the Sea (the LOS Convention). The report also analyses how the LOS Convention’s permanent dispute resolution body - the International Tribunal for the Law of the Sea (ITLOS) - has applied Article 290 in a number of cases: Southern Bluefin Tuna (1999), MOX Plant (2001), Land Reclamation by Singapore in and around the Straits of Johor (2003) and ARA Libertad (2012). Main focus of the examination is placed on how ITLOS has dealt with the two key criteria for its competence to prescribe, modify or revoke provisional measures under Article 290, paragraph 5, that is, the criteria of "urgency" and "prima facie"-jurisdiction.