This study aims to investigate the effect of Emotion-Focused Acceptance and Commitment Therapy (ACT) group psychotherapy on obsessive-compulsive disorder (OCD) symptom severity. Participants with OCD will be randomly assigned to either an ACT-based group psychotherapy arm or a supportive group psychotherapy arm. Each arm consists of 10 to 12 weekly sessions of 2 hours. Symptom severity, psychological flexibility, emotional awareness, functioning and quality of life will be assessed before and after the intervention.

This randomized controlled trial investigates the efficacy of an Emotion-Focused Acceptance and Commitment Therapy (ACT) protocol in adults diagnosed with Obsessive-Compulsive Disorder (OCD). Participants will be recruited from the psychiatry outpatient clinic of Goztepe Prof. Dr. Suleyman Yalcin Sehir Hastanesi.

Eligible participants will be randomly assigned to one of two arms:

ACT-based group psychotherapy: Structured group therapy targeting emotional awareness, acceptance of emotional experiences, cognitive defusion, present-moment focus, values clarification, and committed action. Groups will consist of 8-10 participants, meeting once weekly for 10-12 sessions of 2 hours each.

Supportive group psychotherapy (active control): Unstructured supportive group therapy aimed at providing emotional support, enhancing coping with stress, and maintaining current functioning. Groups will consist of 8-10 participants, meeting once weekly for 10-12 sessions of 2 hours each.

Assessments will be conducted at baseline and post-treatment using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), Dimensional Obsessive-Compulsive Scale (DOCS), Vancouver Obsessional Compulsive Inventory (VOCI), SF-36 Quality of Life Scale, Acceptance and Action Questionnaire-II (AAQ-II), Hospital Anxiety and Depression Scale (HADS), and Toronto Alexithymia Scale (TAS-20).

Inclusion Criteria:

• Diagnosis of Obsessive-Compulsive Disorder according to DSM-5 criteria
• Age between 18-65 years
• Minimum literacy level
• Willingness to participate and providing informed consent

Exclusion Criteria:

• Age over 65 years
• Diagnosis of alcohol or substance use disorder
• Comorbid psychotic disorder or intellectual disability
• Any change in psychiatric treatment (medication or psychotherapy) in the last 3 months
• Comorbid psychiatric disorder that would impair group therapy compliance
• History of cognitive impairment due to dementia, organic brain syndrome or other neurological/organic pathology

This is an open-label study. Due to the nature of psychotherapy interventions, blinding of participants and therapists is not possible. Outcome assessors are not blinded.