This research paper aims to characterize Mathematical Reasoning (MR) in teaching and learning of mathematics in high-school education. To achieve this goal and reveal the status of Mathematical Reasoning as a concept, we analyze the content of curricula and official textbooks of the initial and second year of high school in Morocco. Our analytical framework focuses on the commognitive perspective, exploiting the different components of MR presented in literature. The results obtained from this study using a quantitative approach show that MR occupies a central place in mathematics education at Moroccan high school, but the use of some structural and procedural aspects is still too limited.