The purpose of the study was to investigate the effect of conceptual change-oriented instruction accompanied by computer-based interactive conceptual change text (CBICCT) on 11th grade students understanding of electrochemistry. The study was conducted in a high school in Ankara with 66 students enrolled in two science classes. A quasi-experimental design was used. The classes were assigned to groups; one as a control group and the other as an experimental group. While the control group was given traditional instruction, the experimental group was given conceptual change-oriented instruction accompanied by CBICCT. The Electrochemistry Concept Test (ECT) was administered before and after treatment. To investigate possible covariates, the Science Process Skills Test (SPST) was administered after treatment. The gain scores of ECT were analyzed with two-way ANCOVA when SPST scores were controlled as covariates, and the results showed that the experimental group developed a significantly better understanding of concepts than the control group. The results also showed that there was no mean difference between males and females and no interaction effect between instruction method and gender.