Assessment options are extremely limited for the evaluation of treatment outcome in a specific phobia of vomiting (emetophobia). We aimed to assist researchers and clinicians in the measurement of cognitive processes and behaviors that are characteristic of the disorder for treatment planning and outcome measurement. We developed the specific phobia of vomiting inventory (SPOVI). A series of measures, including the SPOVI, were given to two groups: a group diagnosed with a specific phobia of vomiting and a community control group. Item characteristics, reliability, and factor structure were analysed. Convergent validity with measures of related constructs was determined. The SPOVI was found to have good reliability and validity in the measurement of a phobia of vomiting. The scale has a two-factor structure, with one factor characterised by avoidance symptoms and a second factor comprised of threat monitoring. It is sensitive to change during treatment. The results provide initial evidence of the psychometric qualities of the SPOVI and its suitability for use in clinical practice and research.