The purpose of the study was to investigate the effect of video-assisted conceptual change texts on 12th grade students' understanding and alternative conceptions concerning the gas concept. Within the quasi-experimental design, the study was conducted with 41 12th grade students who were willing to participate in the study. In the design, one experimental group (N = 19) who is taught by using Video-Assisted Conceptual Change Texts and one comparison group (N = 22) who is taught in a traditional manner were used. Students' understanding and alternative conceptions of gas concept were evaluated with a pretest/posttest research design using a true-false test which is consisted of 29 statements. Statistical tests indicated that the test is reliable (with KR-20 reliability of 0.76). The analysis of the findings revealed statistically significant differences between the experimental and comparison groups with respect to conceptual understanding of the gas concept after the treatment. In addition, the findings indicated that each group showed progress in eliminating their alternative conceptions, but the experimental groups were better overall. In conclusion, it was suggest that Video-Assisted Conceptual Change Texts may be an effective way for teaching the gas concept and curriculum designers and textbook writers should take into consideration these strategies when developing new science curriculum. For further work, similar studies can be constructed for other chemistry topics or concepts with larger sample sizes. (C) 2013 The Authors. Published by Elsevier Ltd.