The volatile organic compounds (VOC_S) produced by 12 algal species belonging to different algal groups were identified. The studied species were grown for two weeks and included: Oscillatoria agardhii (two isolates), Oscillatoria limnetica, Oscillatoria limosa, Microcystis aeruginosa, Chroococcus limneticus, Spirulina  platensis, Anabaena sphaerica, Nostochopsis wichmannii (blue-green algae), Cosmarium lavae, Ankistrodesmis acicularis (green algae) and Nitzschia linearis (diatoms). Retention indices and mass spectral data were used to identify about 100 components analyzed by GC-MS. The major abundant VOC_S detected are cyclohexane, heptane, cyclopentane, dodecane, tridecane, octadecanoic acid, 9-octadecanoic acid and undecanoic acid. Fatty acids and benzene derivatives were the most compounds identified in all algal species. Most of volatile organic sulfur compounds were detected in the blue-green species. Consequently, the two isolates of O. agardhii emphasize the role of nitrate concentration contained in the algal media in the production of both geosmin and 2-methylisoborneol.