ABSTRAKPenelitian ini bertujuan untuk menghasilkan produk berupa modul fisika berbasis guided inquiry yang layak, efektif, dan praktis. Kelayakan modul ditinjau dari validasi modul yang selanjutnya digunakan untuk meningkatkan kemampuan berpikir kritis peserta didik. Desain penelitian yang digunakan adalah model 4D yang terdiri dari define, design, develop dan disseminate. Teknik pengumpulan data menggunakan lembar validasi, instrumen tes kemampuan berpikir kritis dan angket respon peserta didik terhadap modul. Data validitas dianalisis dengan menentukan CVI oleh validator ahli. Hasil analisis CVI modul fisika berbasis guided inquiry oleh dosen ahli sebesar 0,99 yang termasuk kategori sangat baik, sedangkan hasil analisis CVI oleh praktisi sebesar 0,89 yang termasuk kategori sangat baik. Data pretest dan posttest dianalisis untuk menentukan peningkatan kemampuan berpikir kritis peserta didik melalui uji n-gain. Hasil analisis data diperoleh rata-rata n-gain sebesar 0,44 dengan kategori sedang yang menunjukkan terjadi peningkatan kemampuan berpikir kritis. Berdasarkan hasil analisis angket respon peserta didik terhadap modul menunjukkan kriteria positif dengan perolehan rerata sebesar 76,9%. Hasil tersebut dapat disimpulkan bahwa produk yang dikembangkan sangat layak, efektif, dan praktis digunakan dalam pembelajaran. Kata kunci: modul, guided inquiry, berpikir kritis. ABSTRACTThis study aims to produce a product in the form of a physics module based on guided inquiry that is feasible, effective, and practica used. The feasibility of the module is viewed from the module validation which is then used to improve students' critical thinking skills. The research design used is the 4D model which consists of define, design, develop, and disseminate. Data collection techniques used validation sheets, critical thinking skills test instruments, and student response questionnaires to the module. Validity data were analyzed by determining CVI by expert validators. The results of the CVI analysis on the product by expert lecturers were 0.99 which was in the very good category, while the results of the CVI analysis by practitioners were 0.89 which was in the very good category. The pretest and posttest data were analyzed to determine the increase in students' critical thinking skills through the n-gain test. The results of data analysis obtained an average n-gain of 0.44 in the medium category which indicates an increase in critical thinking abilities. Based on the results of the questionnaire analysis, the responses of students to the module showed positive criteria with an average acquisition of 76.9%. These results can be concluded that the product developed is very feasible, effective, and practical to use in learning. Keywords: module, guided inquiry, critical thinking.