Has done the research development of Science Mobile Learning Application (SMLA) with the aim of: (1) generate SMLA, (2) describe the development stage SMLA media, (3) determine the feasibility of SMLA. The main benefit of SMLA is can be used as an alternative learning resource for students that can be used anywhere and anytime. This research uses Thiagarajan 4D models that consist of 4 stages among others, define, design, develope, and disseminate. In this research, three stages to develope stage just because of time constraints. Limited test conducted on eighth grade of MTs Miftahul Gondang Ulum, Mojokerto many as 15 students. Data analysis is a quantitative descriptive analysis. The results showed that the developed SMLA media feasible for use as an alternative learning media. Science teacher assessment results have been good at SMLA media, earned media display percentage to 76.67% and 76.39% of the media material. Students gave positive responses (93.98%) against SMLA media to display aspects of media, materials, and student interest. This suggests that the media SMLA the theme has a decent optical instrument used in the learning process and are ready to proceed to the next stage, namely the spread. Keywords: SMLA, optical tools, 4D models, Junior High School Grade VIII.