Introduction: Repetitive negative thinking (RNT) is one of the most important common trans diagnostic factors in the development and maintenance of emotional disorders. Aim of this study was to investigate the psychometric properties of Repetitive Thinking Questionnaire-10 items (RTQ-10 (.Method: In this cross-sectional study, 651 students of Tehran Universities was selected by multistage cluster sampling method and completed Repetitive Thinking Questionnaire, Beck Depression Inventory-II, Beck Anxiety Inventory, Positive and Negative Affect Schedule (PANAS), The Penn State Worry Questionnaire (PSWQ) and Ruminative Response Scale.The construct validity was used to determine exploratory factor analysis, Cronbach’s alpha coefficients was performed to determine the internal consistency and correlation coefficient of Repetitive Thinking Questionnaire-10 items (RTQ-10) with scales of measuring anxiety, depression, rumination, worry, positive and negative affect was used to assess convergent and divergent validity.Results: The results showed of Repetitive Thinking Questionnaire-10 items (RTQ-10) has single-factor structure with good test-retest reliability (0.76) and high internal consistency (0.91). The results also showed that this questionnaire has favorable convergent validity with depression, anxiety, negative affect, rumination and worry along with divergent validity with positive affect.Conclusion: Overall, the results provide evidence based on favorable reliability and validity of Repetitive Thinking Questionnaire-10 items (RTQ-10) as major tool for assessment of trans diagnostic factor namely negative repetitive negative thinking among Iranian students.