Five green algae, namely Chlamydomonas reinhardtii, Scenedesmus obliquus, Chlorella vulgaris, Chlorella minutissima, and Botryococcus braunii, and three cyanobacteria, namely Anabaena variabilis, Nostoc muscorum and Westiellopsis prolifica, were investigated for their ability to generate power. Voltage and current in algal culture was measured against distilled water and growth media. Maximum power and power density against water were produced with B. braunii (0.6 nW, 0.3 mW/m(3)). Maximum power and power density against media was produced with C. minutissima (21.3 nW, 0.106 mW/m(3)). Addition of catalysts Fe2O3 and Mn2O3 led to increase in voltage and power in most of the algal species studied.