Phycocyanin extraction from cyanobacteria Spirulina platensis was optimized using factorial design and response surface techniques. The effects of temperature and biomass-solvent ratio on phycocyanin concentration and extract purity were evaluated to determine the optimum conditions for phycocyanin extraction. The optimum conditions for the extraction of phycocyanin from S. platensis were the highest biomass-solvent ratio, 0.08 g mL(-1), and 25 degrees C. Under these conditions it's possible to obtain an extract of phycocyanin with a concentration of 3.68 mg mL(-1) and purity ratio (A(615)/A(280)) of 0.46. (c) 2006 Elsevier Ltd. All rights reserved.