Abstract. Microalgae are promising sources of biofuel due to its production capacity of lipid that can be utilized as raw material for biodiesel production, especially Nannochloropsis oculata and Chlorella vulgaris. The lipid produced can be converted into biodiesel through transesterification reaction using homogenous or heterogeneous catalysts. Heterogeneous catalysts are more advantageous than homogeneous catalysts due to its solid form that eases the separation of catalysts from the products. In this research, NaOH/zeolite heterogeneous catalyst is utilized with varying Na loadings in the zeolite to observe its effect towards the yield of biodiesel produced from N. oculata and C. vulgaris. The best result was obtained with Na loading concentration of 20.5%. The biodiesel yields obtained from the lipids are 83.5% from N. oculata and 98% from C. vulgaris. The biodiesels contain 47.15% of saturated fatty acid methyl esters from N. oculata and 56.41% from C. vulgaris.