To understand the potential of cultivating tropical marine diatom Thalassiosira sp. to produce biofuel, biodiesel product properties and growth characteristics of Thalassiosira sp. in three different media were investigated. After medium evaluation, significant Thalassiosira sp. cell growth was observed in both Walne and enriched seawater media, but not in plain seawater medium. The microalgae grew well in alkaline condition (pH range of 8.0-8.8). The average biomass density cultured in Walne and enriched seawater media on the 6th day was 4.36 and 2.50 g L-1, respectively. Based on ESI-IT-MS spectra, the TAGs of algal oil were identified as POP, POO, and SOO, and the FAMEs as oleic acid methyl ester. The oil productivity of Thalassiosira sp. cultured in Walne and enriched seawater media were 150 and 290 mu L L-1 d(-1), respectively. The density and kinematic viscosity of Thalassiosira sp. biodiesel were 0.857 g mL(-1) and 1.151 mm(2) s(-1). (C) 2011 Elsevier Ltd. All rights reserved.