Abstract: Growth and photosynthesis of Spirulina maxima grown in different CO2 concentrations and light intensities had been studied. In low light intensity, no significant differences were observed in specific growth rate when the algae were cultured in different CO2 concentration, and so were the Pmax, α and Ik. But in high light intensity, the algae grew faster in high CO2 concentration compared to low CO2 concentration, the specific growth rate being 0 394d-1,0 475d-1,respectively. No significant differences were observed in Pmax, α and Ik in the fifth day. However, significant differences in Pmax, α were found in the eighth and eleventh day.