The problem behind this research is the low critical thinking ability of high school students in Kuningan, West Java. It is shown by there are still students who are still difficult in conducting the activities of asking and expressing opinions during discussion, besides there are still students who do not listen when the learning process takes place, it is also difficult to solve problems in learning. This study aims to determine the effectiveness of increasing students' critical thinking skills through the development of multimedia-based learning media. The method used in this study is the Research and Development (R n D). The research subjects used were high school students in Kuningan Regency. From the results of the study it is known that: Multimedia developed is effective in improving students' critical thinking skills.