Background: Emotional dysregulation and impaired attachment are potential contributors to the development of psychopathology in adolescence. This raises the question of whether oxytocin (OT), the paradigmatic "attachment hormone," may be beneficial in such contexts. Recent evidence suggests that intranasal administration of OT increases affiliative behavior, including trust and empathy. OT may also facilitate social reciprocity by attenuating the stress response to interpersonal conflict. To date, few studies have investigated the effects of intranasal oxytocin (IN-OT) on neurophysiological emotion regulation strategies in healthy adolescents, particularly during parent-adolescent interaction. To understand these mechanisms, our study will examine the effects of IN-OT on emotion regulation in adolescents during parent-adolescent stressful interactions, and on each adolescent's visual and neurophysiological strategies when visualizing attachment-related pictures. We hypothesize that IN-OT will influence psychophysiological outcomes under conditions of stress. We predict that IN-OT will momentarily increase feelings of safety and attenuate stress and hostile behavior during conflict situations. OT may also enhance attachment security by increasing comfort and proximity-seeking, and reducing neurophysiological hyperactivation. Objective: The objective of this study is to evaluate the effects of IN-OT on insecure adolescents by studying their behavior and discourse during a disagreement with one of their parents. Their neurophysiological responses to pictures eliciting attachment-related emotions and their visual exploration strategies will also be investigated. Methods: In this randomized, double-blind, placebo-controlled parallel-group design, 60 healthy male adolescents classified as insecurely attached will receive 24 international units (IU) of IN-OT versus placebo (PB), 45 minutes before the experimental tasks. Each adolescent will then be invited to engage in an experimental conflict discussion with one of his parents. The conflict session will be videotaped and coded for verbal and non-verbal interaction behavior, using the Goal-Corrected Partnership in Adolescence Coding System (GPACS). Each adolescent will then be asked to visualize attachment-related pictures on a screen. Eye-tracking (ET) and neurophysiological responses, including electrodermal activity (EDA) and heart rate (HR), will be recorded simultaneously and continuously during attachment-related picture viewing (Besancon Affective Picture Set-Adolescents, BAPS-Ado). Results: Enrollment for the study was completed in May 2016. Data analysis commenced in July 2016. Study results will be submitted for publication in the winter of 2017. Conclusions: OT is a complex molecule with many facets that are not yet fully understood. This experimental protocol will increase scientific and clinical knowledge of emotion regulation skills in insecure adolescents by assessing the impact of IN-OT on parent-adolescent interaction and on the visual processing of attachment-related emotions. Positive results could lead to therapeutic uses of IN-OT to treat emotion dysregulation in adolescence.