Abstract: The photoinhibition and its recovery were studied in Spirulina maxima grown in high CO2 concentration. S. maxima grown in high CO2 concentration showed photoinhibition when exposed to high PFD, but the decrease in net photosynthesis was smaller compared to that grown in low CO2. S. maxima grown in low CO2 concentration appeared more sensitive to the high PFD treatment as compared with that grown in high CO2 concentration. The recovery of S. maxima grown in different CO2 concentrations was very similar when placed under low PFD, while no recovery was observed in the dark or under the low PFD with the presence of chloramphenicol.