Introduction: Cognitive distortion seems to be a potential force in shaping criminals and antisocial behaviour within an individual. Unfortunately there is no valid Malay psychometric instrument available to measure cognitive distortion in Malaysian settings, especially in prisons. There is an urgent need to have a valid and reliable Malay psychometric instrument to assess the cognitive distortion among Malaysians. Therefore, the present study aimed to validate “How I Think” Questionnaire into the Malay language (henceforth, HIT-M). Methods: A cross-sectional study was conducted among inmates (n= 150) incarcerated within two prisons in Peninsular Malaysia. The validation study commenced with Forward-Backward translations and was followed by content and face validities. Later, construct validity was
performed via Exploratory Factor Analysis using Principal Component Analysis. Varimax rotation was applied in order to optimize the factor loadings on the extracted component. Finally, reliability testing was
performed to determine the internal consistency of the items which was done using Cronbach Alpha coefficient method (α). Findings: Initial factor loadings resulted in 11 factors with a total variance of 74.1%. Next, factor analysis was repeated by extracting the items into a four factor structure parallel to the theoretical construct. Items with factor loadings above 0.40 were retained as acceptable factor loadings. After considering factor loadings, item correlation and content of items, the final version of HIT-M consisted of 24 items. The internal consistency of HIT-M was 0.90 which was considered good. Conclusion: HIT-M is a valid and reliable psychometric instrument to measure and assess cognitive distortion among Malaysians.