This study aims to analyze the conception, threshold concept, and troublesome knowledge in redox reactions. This research used a descriptive qualitative method which included analyzing several journal articles about conception and conducting interviews with five chemistry teachers to get information about threshold concepts and troublesome knowledge. Based on a journal analysis related to the conception for redox reactions, the majority of students correctly answered questions about the concept of defining oxidation numbers based on the binding and releasing of oxygen, determining reducing and oxidizing agents. Conversely, most students experienced misconceptions on the concepts of oxidation and electron transfer, such as in assuming the charge on polyatomic molecules and ions is an oxidation number, changes in ion charge and polyatomic molecules to identify the oxidation and reduction reaction species. Meanwhile, the threshold concept for redox reactions comprised of the symbol of elements, chemical formulas, nomenclature, chemical materials, the constituent particles, and electronegativity. Whereas troublesome knowledge for redox reactions included complexity in determining oxidation numbers, complexity in using definitions, and language use.