This study aims to produce an electronic module based on the Case Method that is feasible and effective in improving students' higher-order thinking skills in the material of Indonesian History during the Reformation Period. This research method uses research and development methods using the ADDIE development design. The research stages of the ADDIE development model consist of Analysis, Design, Develop, Implement and Evaluate. The research subjects were students of the Department of History Education, State University of Medan class 2019. Research data were obtained using questionnaires and tests. The research instrument used validation sheets, student response questionnaires, and tests of higher order thinking skills. Validation data and student response questionnaires were analyzed using the product trial eligibility criteria. Higher order thinking skills test data were analyzed by comparing the test results before and after using the electronic module. The results of the study show 1) the electronic module developed has a good category based on the assessment of material experts with a content feasibility aspect score of 3.73 and a presentation feasibility aspect score of 3.5. 2) the developed electronic module has a good category based on the assessment of media experts with a score of 3.6. 3) the developed electronic module has a good category based on a student response questionnaire of 3.66. 4) the developed electronic module can improve students' higher order thinking skills with an average score of the initial test before using the electronic module of 64.5 and the average score of the final test after using the electronic module of 80.6.