This article presents and illustrates a proposed application of concept maps in chemistry teaching in high schools. The students were provided with the "concept lables" necessary for map building in three different ways. The analysis of the students' maps at different stages of the learning process led to the recognition of the three types of cognitive events which seem to correspond to the same number of restructuring stages in the conceptual organization. This can enable the teacher to characterize the changes produced in the learners' conceptions by teaching / learning activities. Three examples of the use of concept maps in chemistry teaching are reported and discussed with reference to: atomic structure, oxidation-reduction and thermodynamics.