Self-report instruments are useful tools for the assessment of psychopathological symptoms such as obsessive-compulsive symptoms. The Padua Inventory (PI) is a measure that has been widely used in clinical and research settings and studied in several countries.

This study explores the psychometric properties and factor structure of the Portuguese version of the PI.

Translation and translation-back of the original version were executed. A total of 847 participants (468 women and 379 men) from the general population was recruited through a snowball procedure and completed the PI and other mental health measures. The data set was randomly split in order to conduct principal component analysis (PCA) and confirmatory factor (CFA) analysis in two different samples. Moreover, internal consistency, convergent and discriminant validity and test-retest reliability analyses were conducted.

From the PCA analysis four factors emerged, comprising clusters of items related to doubting/impaired control over mental activities, contamination/washing/cleaning, checking and worries about losing control over motor behaviors. CFA results revealed that the model presented a poor fit to the data and indicated that the model would benefit from the establishment of correlations between pairs of error terms of items with identical contents. The PI exhibited excellent internal consistency, good test-retest reliability and good convergent and discriminant validity.

The PI Portuguese version showed a similar factor structure to the one presented in other studies and revealed good psychometric properties. Nevertheless, results from the CFA suggest that shortening the PI may be advantageous.