10.22376/ijpbs.2019.10.1.p1-12 Volume 10 Issue 2 2019 (April-June) Due to the awareness of adverse effects of conventional fuels to environment and the frequent rise in crude oil's price, the need for sustainable and environment friendly alternate source of energy has grown manifold in recent years. Biodiesel is proved to be the best replacement for diesel because of its unique properties like significant reduction in green house gas emissions, non-sulfur emissions, non-particulate matter pollutants, low toxicity. The most widely used feedstocks for biodiesel production were vegetable oils. But beside this traditional feedstock, microalgae is also of growing interest as a potential feedstock for biodiesel production due to its high lipid content when cultured under certain environment. In this work, biodiesel has been produced from Castor oil and lessThan i greaterThan Nannochloropsis Salina lessThan /i greaterThan . The Castor oil methyl ester production has been optimized at 93.6% yield at catalyst concentration 1.5%, alcohol to oil ratio 6:1 (mol/mol), at 55 lessThan sup greaterThan o lessThan /sup greaterThan C for 120 minutes of reaction time. The lipid content from lessThan i greaterThan Nannochloropsis lessThan /i greaterThan has been extracted and converted into methyl ester using Soxhlet extraction (using two different solvents- n-hexane and chloroform and methanol mixture) followed by transesterification and using microwave assisted in-situ transesterification. The highest biodiesel from microalgae is 20% on dry weight basis. The results showed that the production of methyl ester from Castor oil is more compared to lessThan i greaterThan Nannochloropsis Salina lessThan /i greaterThan methyl ester and therefore it was concluded that Castor Oil methyl ester is a better choice for diesel blending. P.A. SATYANARAYANA, ANIKET DAS, P. SRINU, V. SRIDEVI, RITESH RANJAN Biodiesel, Castor oil, Nannochloropsis Salina, Soxhlet extraction, GC-MS, Transesterification. 45-53