Poorer neurocognitive performance in patients with Obsessive-Compulsive Disorder (OCD) is well documented in the literature. Thus, we investigated the social and neurocognitive performance of OCD-diagnosed individuals in this study. Moreover, we aimed to examine the neuropsychological predictors of treatment response and the therapeutic effect on social and neurocognitive functions of Cognitive Behavioural Group Therapy (CBGT) in OCD patients. Social and neurocognitive tests were applied before and after ten cognitive behavioral group psychotherapy sessions. OCD group showed worse performance in Rey Auditory Verbal Learning and Memory Test (p = 0.049), Wisconsin Card Sorting Test number of the completed category (p = 0.011), number of trials (p = 0.03), perseverative errors (p = 0.043), Trail Making Test (TMT)-A (p = 0.032) and TMT-B (p = 0.015) compared to the healthy controls. Reading the Mind Through Eye Test performances were similar in the patient and control groups. After CBGT, patients’ scores on Yale-Brown Obsession Compulsion Scale, Beck Depression Inventory, Obsessive Beliefs Questionnaire, and Obsession Compulsion Inventory-R decreased. When results were corrected for practice effect, no improvement in social and neurocognitive test performance was found. There was no relationship between treatment response and pretreatment social and neurocognitive test performance. Poor cognitive functions might be trait features of OCD.