The purposes of this study were to determine: 1) the attitudes and motivations of pre-service science teachers in learning Hess' Law using multimedia based on multiple representations (macroscopic, microscopic, and symbolic) of Hess' Law; 2) the learning outcomes of the participated pre-service science teachers after experiencing the learning through the multimedia, and 3) the effectiveness of the multimedia in improving the mastery of pre-service science teachers' science processes and concepts about Hess' Law. The method used in this study is quasi-experimental; pre-test and post-test were addressed through a questionnaire and test. Data analysis was performed through multimedia quality data, based on the multiple representations and t-test. The results showed that the pre-service science teachers could learn Hess' Law material more efficiently, faster, more actively, and more independently. They were also motivated to learn by using the multimedia. The results of the t-test for the difference before and after treatment was significant (p <0.005). Suggestions and recommendations for teacher educators, policymakers, and pre-service science teachers are provided.