The influence of temperature and pH on biomass production and protein biosynthesis in a Spirulina sp. isolated from an oil-polluted brackish water environment in the Niger Delta was studied. The isolated organism was identified on the basis of its phenotypic characteristics such as nature and direction of helix, temperature, pH and salt tolerance ranges. Biomass concentration in the culture media was calculated as cell dry weight. The combination of 30 degrees C and pH 9.0 gave the highest values of 4.9mg/ml and 48.2 g/100g for biomass and total crude protein, respectively. The effect of pH was modulated by temperature and vice versa during biomass production. This native isolate of Spirulina sp. offers a good source of natural protein that could be easily accepted by rural communities as single cell protein in the form of feed, food and health supplement when properly processed. (c) 2006 Published by Elsevier Ltd.