2-Methylisoborneol (MIB) and geosmin (GSM) are taste and odor compounds produced as secondary metabolites by some cyanobacteria and actinomycetes, and thus they can be present in some drinking water sources. The removal efficiency, intermediate by-products, and degradation pathway of MIB and GSM in synthetic water by ozonation were studied. The results show that ozone is efficient in removing MIB and GSM from an aqueous solution, depending on pH and the initial MIB and GSM concentration. Ozonation of algal suspension was also studied and the removal efficiency of GSM mainly produced by Lyngbya kuetzingii can reach 99.91% although the ozonation could damage the algal cells and release the intracellular organic compounds. The degradation by-products of MIB or GSM were identified by gas chromatography-mass spectrometry and dehydration and open ring compounds are the main by-products. Possible degradation pathways for the ozonation of MIB and GSM were proposed. (c) 2013 Elsevier B.V. All rights reserved.