Since chemical bonding subject generally covers abstract concepts, it is one of the difficult subjects for students to understand. Therefore, most students have misconceptions about chemical bonding and its types. The aim of this study is to investigate eleventh grade students’ understanding about covalent bonding and to determine their related misconceptions. In the study, a test comprising four open-ended questions and semi-structured interviews were employed to collect data. The test used in the study was administered to 58 eleventh grade students in a public high school. 10 students selected randomly from the sample were also interviewed. Sound understanding, partial understanding, partial understanding with a specific misconception, specific misconceptions and no response/no understanding categories were used for analyzing students’ responses for both test and interview questions. Results showed that students had many misconceptions especially on the types or properties of atoms which form covalent bonding, how covalent bonding was formed, the types of covalent bonding, and the characteristics of giant covalent structures. Study presents some suggestions for teachers, curriculum developers and textbook authors to make students understand the subjects easier and to remediate their misconceptions.