Penelitian ini bertujuan untuk menghasilkan e-Book berbasis critical thinking yang layak (valid, praktis, dan efektif). Penelitian ini merupakan jenis penelitian pengembangan menggunakan model pengembangan ADDIE (Analysis, Design, Development, Implementation, dan Evaluation). Teknik pengumpulan data yang digunakan adalah kuisioner, observasi, dan tes dengan subjek 30 peserta didik kelas XI MIPA di Madrasah Aliyah Negeri Kota Mojokerto. Validitas e-Book ditinjau dari aspek bahasa, media, materi, dan berpikir kritis. Kepraktisan ditinjau dari keterlaksanaan pembelajaran dan berpikir kritis berbasis proses. Keefektifan ditinjau dari evaluasi dan respon peserta didik. Semua aspek penilaian validitas, keterlaksanaan pembelajaran, berpikir kritis berbasis proses, dan respon peserta didik menggunakan skala Likert sedangkan evaluasi dinilai tuntas apabila skor akhir  KKM di sekolah.        e-Book berpikir kritis dinyatakan layak apabila persentase semua kriteria kelayakan 61%. Hasil penelitian menunjukkan:               1) Persentase validitas bahasa sebesar 87,50%, persentase media sebesar 91,25%, persentase materi sebesar 92,86%, dan persentase berpikir kritis sebesar 90,00% sehingga e-Book yang dikembangkan dapat dinyatakan valid; 2) Persentase keterlaksanaan pembelajaran sebesar 93,73% dan persentase berpikir kritis berbasis proses 92,22% sehingga e-Book yang dikembangkan dapat dinyatakan praktis; 3) Hasil evaluasi peserta didik menunjukkan bahwa 100% peserta didik mendapatkan nilai di atas KKM dan persentase respon peserta didik 80,56% sehingga e-Book yang dikembangkan dapat dinyatakan efektif.

Kata Kunci: e-Book, berpikir kritis.

This research aims to produce an e-Book based on worthy critical thinking (valid, practical and effective). This research is development research by using the ADDIE development model (Analysis, Design, Development, Implementation, and Evaluation). Data collection techniques used questionnaires, observations, and test with the subjects are 30 students of class XI MIPA in Madrasah Aliyah Negeri Mojokerto City.  The validity of e-Book is reviewed from the aspects of language, media, material, and critical thinking. Practicality is reviewed from the implementation of learning and critical thinking based on a process. Effectiveness is reviewed from the evaluation and response of students. All aspects of assessment of validity, the implementation of learning, critical thinking based on a process, and students responses are using a Likert scale whereas the evaluation is rated complete when the final scores   KKM in school. The critical thinking       e-Book is claimed to be feasible if the percentage of all eligibility criteria is  61%. Research results postulate show: 1) The percentage of language validity is 87,50%, the percentage of media is 91,25%, the percentage of material is 92,86%, and the percentage of critical thinking is 90,00% so that the developed     e-Book can be claimed valid; 2) The percentage of learning accomplishment is 93,73% and the percentage of critical thinking based on process is 92,22% so that the developed e-Book can be claimed practical; 3) Students evaluation results show that 100% of students get a score above the KKM and the percentage of students responses 80,56%% so that the developed e-Book can be claimed effective.

Keywords: e-Book, critical thinking.