≫Procedural Transparency in International Investment Arbitration Proceedings with particular regard to the UNCITRAL Rules on Transparency≪: In the past, international investment arbitration proceedings were mostly held confidentially, which led to public criticism. The thesis discusses the priciples of procedural transparency, analyzes the UNCITRAL Rules on Transparency and compares them with other arbitration rules. Possible tensions with other procedural principles are examined and suggestions are made for an effective procedural management by the arbitral tribunal.