The aim of this study was to investigate the effectiveness of instruction supplemented by conceptual change texts (CCTs) over traditional instruction on students' understanding of electrochemical (galvanic and electrolytic) cell concepts. The participants of the study consisted of 64 students from the two classes of a high school located in Turkey. Classes were randomly assigned to experimental group, which was exposed to CCTs as a supplementary material, and to control group, which was exposed to traditional instruction. A 23-item multiple-choice test was developed assess students' conceptual understanding of electrochemical cells. This test was administered to both groups before and after the instruction. The results of ANCOVA indicated that students who were instructed by using CCTs had better conceptual understanding of electrochemical cells than those experiencing traditional instruction when their prior electrochemical cell concepts understanding was statistically controlled. The findings of this study suggest that CCTs can be used as a cost- and resource-effective supplement to classroom instruction to promote students' understanding science concepts. © 2007 Springer Science+Business Media, LLC.