The purpose of this study is to highlight the acquired knowledge concerning the acidic and basic solution and recognition of acid and base, and difference according to knowledge to be taught at the level of upper secondary school (grades 11-12) for both French and Turkish students. Data was collected, before and after the relevant teaching was conducted, using a questionnaire containing four open-ended questions from 237 French students, and 207 Turkish students. The results showed that after the received teaching, Turkish students defined acidic and basic solutions using the empirical register. However, most of French students refer to models register. Therefore, this study pointed out that the knowledge relating to acidic and basic solutions taught at grade 9, is more mobilized by grade 11 students than grade 12 students.