The purpose of this study is to determine pre-service chemistry teachers' knowledge of the oxidation number and coordination number in coordination compounds. Data were collected from 31 pre-service chemistry teachers through a 4-question scale, and the second question of the scale consisted of 8 sub-questions. The results showed that the participants had difficulties in defining both the coordination number and the oxidation number of the central atoms/ions in coordination compounds, and they had misconceptions about these concepts. Also, it was revealed that the participants had difficulties in determining both the oxidation number of the central atom and the coordination number in coordination compounds. Participants stated that they had problems in determining the oxidation number because they did not remember the ligand charges, and the coordination number because they did not remember the number of ligand teeth.