The paper engages possibilities of key competences for sustainable development developing at secondary and high schools in ecological education. In the first part of the work are worked out theoretical solutions to ecological education teaching and its current situation in the Slovakia. The second part consist methodology and suggested activities and educational programmes in ecological education for pupils of high school. The objective of the work is suggestion of activities for pupils to develop their key competences in sustainable development during classes and free time classes. It was suggested 7 activities possibly applied in educational praxis. There are discussed some problems in ecological education in the Slovakia and suggested their solution to eliminate shortages of teaching ecology and environmental sciences.