The aim of this study is to determine effect of teaching material based on 5E model on pre-service teachers’ conceptual change ‘acid- bases’ subject. This research was carried out with 25 sophomore pre-service teachers at Artvin Çoruh University Faculty of Education who were enrolled to science laboratory practices course in 2006–2007 instructional term-fall semesters. In this study, one-group pretest-posttest design was used. The study consisted of three phases; in the first part, a concept test with ten open ended questions was employed to determine student’s misconceptions about ‘acid-bases’ subject. In the second part, an activity based on 5E model was developed and implemented as a teaching intervention. In the last part, the concept test was re-administered after the teaching intervention. It was found that pre-service teachers had many misconceptions about acid and bases as found in literature. Moreover, teaching material based on the 5E model is concluded to be quite effective solving misconceptions.