Currently, it's known that the aquatic pollution represents a serious environmental problem, once the harms produced may spread to different ecosystems and reach the human being. The anthropogenic activities are responsible for producing large amounts of pollutants, mainly the organic compounds that can be bioaccumulated or biotranformed. Phenol is the most disseminated and representative pollutant in aquatic environments. Algae are important bioindicators of aquatic environmental pollution, as they suffer intracellular changes in the presence of contaminants. Literature shows that phenol has the capability of inducing an oxidative stress condition during its biotransformation process. In this situation, algae undergo a series of cellular modifications that characterize a defense system against possible oxidative injuries. The defense mechanism involves enzymatic systems, in which the superoxide dismutase (SOD) has an outstanding role, being responsible for converting O₂^.- into H₂O₂ and O₂. In this study it was determined the growth curve of a control culture of the microalga Monoraphidium convolutum during 39 days on adequate temperature, luminosity and nutritional conditions, starting with 10⁴ cells/mL, and estimated through chlorophyll a fluorescence and count of the cell density. The microalga shows a lag phase during the first three days, and achieves the stationary phase around the tenth day. The influence of different concentrations of phenol over the algal growth was verified on a culture initially with 10⁵ cells/mL, during a 48 hours exposition. The obtained IC₅₀ value was 2.9mM, while the IC₂₀ value was 1.3mM. Furthermore, the SOD activity in control culture was measured, and this trial showed a SOD activity of 22.5 ± 11.6 U SOD/ protein mg. The freshwater microalga M. convolutum exhibited an appropriate growth rate, and when confronted to literature references demonstrated good sensibility to phenol. This could indicate that the alga may be a good candidate as a bioindicator in polluted environments.