BackgroundOrganic farming is a relatively new concept in developing countries compared to developed countries. Understanding the factors affecting consumers’ willingness to pay for organic foods is critical to increasing the production of these products. This study aimed to develop and validate a Persian version of the questionnaire for assessing determinants of organic food purchase intention among adults in Tehran, the capital of Iran.MethodsThe study was conducted in a two-phased standardized methodology in 2019. During Phase 1, a draft questionnaire was developed based on a comprehensive literature review. In phase 2, validation of the instrument was performed. Participants included a multidisciplinary expert panel comprising 14 members to evaluate content validity, a sample of lay people to assess face validity (n = 20), internal consistency (n = 300), and test-retest reliability (n = 62). The internal consistency and test-retest reliability were measured using the intraclass correlation coefficient (ICC) and Cronbach’s alpha.ResultsForty-nine of 57 items had a CVR above 0.51 and were retained in the questionnaire. Three items were added to the questionnaire. The average CVI for the questionnaire was 0.97. Cronbach’s α and ICC of the entire questionnaire were 0.86 and 0.93, respectively. Each phase of development progressively improved the questionnaire, resulting in a final 52-item questionnaire divided into 9 dimensions, including knowledge, attitude, subjective norms, health consciousness, environmental concerns, perceived convenience of purchase, perceived cost, sensory characteristics, and purchase intention.ConclusionsThe developed questionnaire appears to be a valid and reliable instrument for examining determinants of consumer intentions to purchase organic food.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40795-023-00731-y.