This study aims to determine the effectiveness of interactive multimedia-based blended learning developed in the subject matter of chemical elements. The effectiveness in terms of improving student learning outcomes by comparing the value pretest and post-test then measured with N-gain. This type of research is developmental research. The procedures in this study refers to Research & Development (R & D) design that carried out only restricted to preliminary field test. The results showed student learning out-comes that used interactive multimedia blended learning as learning media increased with N-gain in the moderate category and in the high category. The conclusions obtained by the interactive multimedia blended learning based on the subject matter chemical element was declared effective used as a medium of learning in terms of student learning outcomes.