This research paper initially presents theoretical references about the conceptualization of the teacher's practical knowledge, some authors define it as a complex, implicit and personal knowledge that directs the teacher's actions. From this perspective, this research is aimed at characterizing the practical knowledge of a Chemistry teacher in practice, taking into account that the teacher not only transmits content and does not only require disciplinary knowledge in their educational practice, since their thoughts and actions are seen immersed in a reality that is complex, dynamic and unpredictable, where they put into play a broad background of knowledge: knowledge of himself, of the context or environment where he directs his practice, disciplinary, didactic, curricular and pedagogical knowledge, among others. In this way, in educational practice, practical knowledge is constructed that distinguishes science teachers. This research will allow the chemistry teacher in practice to recognize and evaluate their practical knowledge, contributing to the reflection, transformation and evolution of it. In such a way that it contributes to improve the teaching-learning process, since it is intended to inquire about the influence of this knowledge in teaching. The methodological proposal to carry out the research is made up of three stages: First, a theoretical analysis, on the conceptual references around this great category of knowledge, a methodological analysis through a case study, highlighting the use of a classroom virtual learning as socialization material and study with the teacher about the subject, which is designed by units, a Likert-type questionnaire, a semi-structured interview, field diaries to record non-participatory observations in the classroom that allow evidence of the relationship between the teacher's thinking and actions around practical knowledge. The construction of the instruments was carried out based on the previous construction of the categories of analysis around practical knowledge which were validated by the thesis director. Finally, a final analysis that allowed the triangulation of the data collected through the different instruments to characterize the practical knowledge of a teacher of chemistry in practice and its influence on the teaching of Chemistry.