Four out of thirty-one algae strains belonging to the order Chlorococcales exhibited good growth on solid media containing n-alkanes. Chlorella vulgaris (397) was able to degrade n-tridecane in cooxidation. The corresponding secondary alcohols and ketones in C2-to C7-position could be identified in the culture broth. The same oxidation products could be found in the media of cultures grown in darkness with the addition of glucose. This demonstrates a subterminal degradation pathway of C. vulgaris.