Self-determination theory defines motivation as a multidimensional concept, with autonomous and controlled motivation as central factors of broader distinctions. Previous research has proven that academic achievements are positively correlated with autonomous motivation. Students from 10 Slovenian grammar schools were involved in empirical study, in which a cluster analysis revealed two motivational profiles: a low quantity motivation group (low controlled and autonomous motivation) and a good quality motivation group (high autonomous and low or average controlled motivation). Statistically significant differences between the two identified motivational profiles were found for students' general as well as chemistry performance in three grades of schooling. Furthermore, a good quality motivation group is also more in favour of autonomy-supportive teaching methods used in chemistry classes. Examination of students' opinions about important chemistry topics, and on the other hand, unimportant ones, and not connected with life, reveals that the basic reason for distinction might lie in the chemistry teacher's approach used while presenting these topics. Some chemistry teachers are not using an autonomy-supportive way of teaching which would contribute to better teaching outcomes; therefore a need for further research on Slovenian chemistry teachers' motivation and their teaching approaches was recognized.