Chlorophyll is a pigment used as colorant in the food, pharmaceutical and cosmetic industries, It can be obtained in considerable quantities from Spirulina platensis biomass. In this work, the cultivation of the microalga was done using urea as the nitrogen source by a fed-batch process. The addition of urea was done in four different modes: intermittent addition every 24 or 48 h, continuous addition by exponentially increasing the added mass, and continuous addition by using a constant mass flow rate. The experiments were carried out at three different temperatures: 27degreesC, 30degreesC and 33degreesC and at a constant light intensity of 3.5 klx. The results showed a positive influence of urea in the growth of Spirulina but no effect on the final chlorophyll content of the cultures. Best results were obtained by continuous urea addition in exponentially increasing amount, at 30degreesC.