This study aims to describe the effectiveness of the inquiry learning model to improve students' cognitive learning outcomes at the temperature and heat of class XI from one public school (SMAN 1 Gerung). This type of research is quantitative descriptive with "One Group Pretest-Posttest Design". The instrument used for this study is the observation sheet applying the inquiry learning model and learning outcomes tests on the cognitive domain (C1 to C6). The results of this study indicate that: (1) the percentage of implementation of learning with inquiry models increases, showing better quality of learning and (2) the percentage of students' cognitive learning outcomes at temperature and heat increases as well.