This study aims to determine the effectiveness of the application of Socratic question-based contextual teaching materials on Thermodynamics material to students' critical thinking abilities. The advantages of physics teaching materials based on Socratic question include: arranged based on the curriculum, the phenomenon of presenting facts or problems of students' daily lives, Socratic-based questions that serve as instructions for students to open initial thoughts about the material to be studied, Students can find their concepts so that the concepts received are more embedded in their mind, and Empirically tested in developing critical thinking skills in physics. The weakness of teaching materials is the limited number of questions that illustrate the application or problems in daily life and the quantity of Socratic questions that are not evenly distributed in each material. The study was conducted using a quasi-experimental method through testing in the experimental class and control class with a total number of test students totalling 129 senior high school students in Malang. The results of the Independent Sample t-test showed that there was a significant difference between the students' critical thinking abilities in physics using a Socratic question-based contextual teaching material product without the application of the product. In addition, it was found that the profil of students' critical thinking abilities in physics using learning products based on Socratic question contextual physics teaching materials were higher than learning that did not use contextual physics teaching materials based on Socratic questions (with critical thinking indicator consist of giving arguments, induction, evaluate, and deciding). These results indicate that learning to use contextual physics teaching materials based on Socratic questions is more effective than learning using teaching materials that are commonly used in developing critical thinking skills in physics on thermodynamic material.