Adolescents exhibit difficulties in behavioral regulation that become more evident when emotional contexts are involved, since these may hinder the development of socially-adaptive behaviors. The objectives of the present study were: to examine the influence of emotional contexts on adolescents' ability to inhibit a prepotent response, evaluated by ERPs, and to determine whether sex differences in response inhibition are observed in adolescents in those contexts. Participants performed a prepotent response inhibition task (Go-NoGo) under 3 background context conditions: neutral, pleasant, and unpleasant. While no differences in accuracy were observed, the presence of emotional contexts did prolong reaction times compared to the neutral context. Also, the unpleasant context caused an enhancement of N2 amplitudes compared to the neutral and pleasant contexts. Also, N2 and P3 latencies were longer in emotional contexts than in the neutral condition during both correct responses and correct inhibitions. No sex differences were found in amplitude, but females showed longer N2 and P3 latencies than males. These results confirm the idea that, in adolescents, unpleasant pictures receive preferential attention over neutral images and so generate greater difficulty in response inhibition. Finally, results demonstrate that sex differences in inhibition control in adolescence were observed only in relation to time-processing.