Besides platinum, various nonnoble metal compounds, when prepared appropriately, are suitable for the electrochemical reduction of oxygen in liquid electrolytes and PEM-fuel cells. Pyrolyzed N4-chelates, such as phthalocyanines, tetraazaannulenes and porphyrins with a central metal atom of iron or cobalt, are a very important group of compounds and have been investigated in the past. It was found that the catalytic activity, especially of phthalocyanines, was high when prepared on carbon black supports at high temperatures (400-900 degrees C). Investigations on tetraazaannulenes and porphyrins yielded similar results. Non-noble metal compounds of cyclame (1,4,8,11-tetraazacyclotetradecane), which are also N4-chelates, were not investigated as thoroughly. However, the catalytic activities of iron and cobalt cyclames were low, compared to those of phthalocyanines. With the (GC-MS) analysis of both decomposition products, it could be shown that the mechanism of the N4-chelate decomposition is of decisive importance for the catalytic activity.