The non-catalytic transesterification of microalgae oil withmethanol was conducted at 300–400◦C, 150–300 bar, MOMR of6–12, and residence time of 0.5–10 min. At 200 bar, 9 molar ratioand 4 min reaction time for temperature from 300 to 400◦C, thereaction conversion increased from 19.3% to 95.5%.