The interpretation and application of article 7(1)(g)-6 of the Statute of the International Criminal Court (ICC), punishing “any other form of sexual violence of comparable gravity” as a crime against humanity, has proved challenging due to its vague and undefined terms. Yet, understanding what this crime entails is primordial in light of the principle of legality. Hence, this study first examines how the actus reus of sexual violence has been defined in international law with a focus on the International Criminal Tribunal for the former Yugoslavia and the International Criminal Tribunal for Rwanda. Second, drawing on the ICC’s applicable law, case law, and scholarship, this study conducts an in-depth analysis of each actus reus requirement of article 7(1)(g)-6 of the Statute of the ICC to clarify their scopes and meanings. While the implications of the “violence” requirement are evident, ambiguities remain for the “act of sexual nature” and “of comparable gravity” requirements. Consequently, this study suggests an “act of sexual nature” to be understood as a conduct that objectively targets the victim’s sexual characteristics, sexuality, or sexual autonomy. Additionally, the cultural context, the rationale behind sexual violence in conflict, and the victim’s physical integrity and personal dignity must also be considered. To assess the gravity of an act, this study further argues, its nature must first be considered, and other criteria in a second step, such as the number of victims, the reiterative character or public commission, the immediate or long-term impact on the victim, or the cultural context.