This 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.