The present study evaluates the effectiveness of an intervention using a mobile app game aimed at reducing sexism in adolescents. A quasiexperimental pretest-posttest study is executed with intervention and control groups. The participants are 369 secondary school students from the province of Valencia, of whom 196 are assigned to intervention and 173 to control group. Hostile and benevolent sexism are assessed at both points in time using theory of ambivalent sexism. The two hours' intervention involved explaining the game's dynamic, implementation and use. The results of applying the programme are evaluated of the two dimensions of sexism in two time periods. Intervention with the app brought about a significant change, reducing sexism in adolescents by between six and 12%. The study highlights the usefulness to make use of information and communications technology (ICT) as a tool for combating sexism and co-educating in equality using gaming strategies to develop non-sexist prosocial competencies.