Background: The importance of valid and reliable instruments for the assessment of factors affecting students' interest in science encouraged the development and validation of a brief Spanish instrument for the measurement of expectancies of success in school science, named SUCCESS. In this study, the psychometric properties of the SUCCESS instrument are further evaluated using different psychometric tests and a different sample than the one included in the original validation study. Material and methods: A sample of 313 Spanish elementary school students enrolled in 4th to 6th grade was drawn by means of convenience sampling techniques. Responses were analyzed in terms of construct and criterion validity, and two reliability indices. Results: Results from confirmatory factor analysis established the unidimensional structure of the instrument, with great model fit indices. Correlation coefficients between the SUCCESS and external measures (i.e. intentions to enroll, enjoyableness, difficulty, auto-efficacy, utility and relevance of school science) provided evidence of criterion validity. Cronbach a and item-total correlation indices supported the internal consistency reliability of the instrument. Conclusions: Taken together, this study further provide evidence to consider the SUCCESS as a valid and reliable tool for the measurement of Spanish elementary school students expectancies of success in school science.