The rapidly growing population and expanding technological activities have accelerated the rate of addition of numerous poisonous pollutants especially the metal ions to the surrounding environment. These pollutants become deleterious due to their mobilization, transport and deposition in the various aquatic as well as terrestrial ecosystems. The cyanobacteria and algae (commonly called together ‘Algae’) constitute the most ancient groups of autotrophic microorganisms and are invariably affected by the presence of metal ions in the environment (Whitton, Arch Mikrobiol 72:353–360, 1970). Algae are the organisms which can resist the metal toxicity by biochemical, chemical and physical mechanisms resulting in cell surface adsorption, metabolism dependent accumulation and precipitation (Gadd GM (1988) Accumulation of metals by microorganisms and algae. In: Rehm HJ (Ed) VCH, Weinheim, pp. 401–434). They instantly interact with metal pollutants differently at cellular level showing different responses and tolerance mechanisms, termed as ‘algae-metal interactions’—which is the basis of phytoremediation process. © Capital Publishing Company 2015.