The growth of the freshwater microalga Scenedesmus obliquus was studied at 30 degrees C in a mineral culture medium with phosphorus concentrations of between 0 and 372 mu M. The values for the specific growth rates, between S-0=0 mu M and S-0=298 mu M, fitted a semistructured substrate-limitation model with mu(m1)=0.0466 h(-1), mu(m2)=0.0256 h(-1) and K-s=0.2 mu M. The specific uptake rate of phosphorus reached a maximum value of q(Sm1)=658.01x10(-4) mu mol P mg(-1) biomass h(-1).