Reassessement of bioenergetic growth yield of Arthrospira platensis was performed by using continuous culture under both autotrophic and mixotrophic conditions. Continuous culture was carried out at dilution rates of 0.017, 0.023 and 0.030 h−1. Under these dilution rates bioenergetic yields ranged between 4.45–6.03 × 10−3 g biomass kJ−1 and between 5.42–7.46 × 10−3 g biomass kJ−1, under autotrophic and mixotrophic conditions respectively. A maximum bioenergetic yield of 8.1 × 10−3 g biomass kJ−1 using an autotrophic culture can be calculated. Pigment accumulation (chlorophyll a and carotenoids) may be related to light irradiance, reaching a maximum pigment concentration under light saturation irradiance. Phycocyanin concentration increased during light limitation.