Abstract: The green microalga strain, Botryococcus braunii KMITL 2, was isolated from a freshwater reservoir in central Thailand, and the effects of light, nitrogen, phosphorus, iron, cultivation time and salinity on lipid production were studied by varying parameters one at a time. When cultured in Chlorella medium containing 222mgL−1 phosphorus () under continuous illumination of 200μEm−2 s−1 with a salinity of 0psu, a maximum lipid content of 54.69±3.13% was obtained. Its high lipid content makes strain KMITL 2 a potential source for biodiesel production in tropical regions. [Copyright &y& Elsevier]