This work aims at optimizing biomass and exopolysaccharide productivities of Botryococcus braunii CCALA 778 grown under simulated Mediterranean climate conditions. The effect of temperature and light irradiance on biomass and exopolysaccharide productivity were studied. Our results show that light:dark cycles lead to higher biomass and sugar productivities in comparison to continuous illumination. The optimal temperature of Botryococcus braunii CCALA 778 ranges from 23 to 26 °C, although it is tolerant to low temperatures (4 °C). The highest exopolysaccharide productivity (0.29 ± 0.05 g exopolysaccharide L− 1 day−1) was obtained during high light irradiance (simulating a summer day) and temperature controlled at 26 °C.