The purpose of this study was to delve into the interaction between pre-service chemistry teachers' pedagogical content knowledge (PCK) and content knowledge (CK) while teaching electrochemistry. Two pre-service chemistry teachers enrolled in practice teaching course in chemistry education program participated in the study. All PCK components were included in the current study. Qualitative methodology was used and the participants were selected through purposeful sampling. Data were collected through electrochemistry content test, Content Representation (CoRe), semi-structured interviews, video stimulated recall interviews, classroom observations and field notes. Results indicated that the level of CK impacted PCK: basic level of CK is a prerequisite for developing PCK, while a high CK does not guarantee a high PCK to the same extent. Pre-service teachers with weak content knowledge had problems in recognizing students' possible misconceptions, using vertical and horizontal relations in the curriculum and using the topic-specific instructional strategies effectively. The level of content knowledge did not have a strong impact on choice of subject-specific instructional strategies, assessing students' understanding, and science teaching orientations of pre-service teachers. This study highlights that the quality of PCK depends on the interaction between content knowledge and the components of PCK. From a methodological perspective, this study demonstrates the possibility of making pre-service teachers' PCK more accessible by utilizing video stimulated recall interviews. Implications for pre-service teacher education aim to support pre-service teachers to establish a bridge between their content knowledge and teaching knowledge through teacher education program.