Microalgae are photosynthetic microorganisms found in aquatic environments around the world. There is interest in using microalgae to capture carbon (CO₂) from industrial off-gas, but sulphur dioxide often present in these gasses increases growing media acidity making it essential to find microalgal strains able to survive in pH 3.0-4.0. High metal concentration, acidity, solar irradiance, and nutrient limitations can instigate the production of protective secondary metabolites with antioxidant potential. Therefore, the antioxidant potential of novel microalgal isolates bioprospected from acidic mine-impacted water systems, identified as Coccomyxa sp. and Chlamydomonas sp., and a culture collection strain Chlamydomonas reinhardtii were tested using three antioxidant assays. Results showed that low pH conditions (pH 3.0) increased biomass production of Coccomyxa sp. but induced the death of C. reinhardtii. Under both pH 3.0 and uncontrolled pH conditions, the bioprospected strains had higher antioxidant potential than C. reinhardtii, with Coccomyxa sp. having the highest potential.