The aim of this study was to assess the effectiveness of violence prevention program over the Internet and to assess the relationship between emotional intelligence, experiencing and committing cyber bullying. The study was conducted on a sample of N=130 students of Gymnasium 1 in Osijek. The instruments used in the research were: Revealing personal information online questionnaire (Milić and Tomašić Humer, 2015), The knowledge of cyber bullying questionnaire (Milić and Tomašić Humer, 2015), Cyber victim and bullying scale (Cetin, Yaman and Peker, 2011) and Emotion management test (Babić Čikeš and Buško, 2013). The results showed that violence prevention program had no impact on the knowledge of cyber bullying, experiencing and committing cyber bullying and revealing personal information online among high school students. However, it has been found statistically significant difference between control and treatment group in experiencing and committing cyber bullying at the starting point of measurement, where the participants of treatment group reported experiencing and committing more cyber violence then control group. Also, results have pointed to a weak, but statistically significant negative relationship between results on the Emotion management test and results on the Subscale of committing cyber bullying. The participants, who scored higher on the Emotion management test, commit less cyber bullying. Finally, it has been found strong statistically significant positive relationship between results on the Subscale of experiencing cyber bullying and the results on the Subscale of committing cyber bullying which means that the participants who committed cyber bullying also experienced it.