In the world energy crisis context, finding sufficient supplies of cheap and clean energy for the future is one of society's biggest challenges and is related to global stability, economic prosperity and quality of human's life. Environmental protection and depletion of fossil fuel supplies are becoming the overriding challenges faced to oil industries. Recently, biodiesel has attracted considerable attention as a renewable, biodegradable, nontoxic and environmentally friendly fuel. However, the lack of oil feedstocks limits the large scale development ofbiodiesel to a large extent. Microalgae have long been recognized as a potential feedstock due to their many advantages for biodiesel production such as their high oil content and rapid biomass production. Oil yield per acre could be 100 times higher than oleaginous plants. They are able to grow extremely rapidly, generally doubling their biomass with in a day. They can be cultivated in large open ponds or in closed photobioreactors located on non-arable land, avoiding competition with conventional agriculture for land resources and consume less water than terrestrial crops. Moreover, microalgae can absorb carbon dioxide as the carbon source for growth and this contributes to both atmospheric CO2 emission mitigation and high biomass production. In this sudy, the authors present the results of research on biodiesel production from a marine microalga Nannochloropsis oculata through the technology of in-situ transesterification, which resulted in a biodiesel yield of 89 percent based on the algal oil. On the other hand, the prediction values of density at 15oC, viscosity at 40°C, flash point, iodine value, cetane numeric value meet the B 100 biodiesel standard of Vietnam. The obtained results suggested that the in situ transesterification technology was a feasible and effective method for the production of high quality biodiesel from microalga.