Binary polymeric beads of sodium alginate and starch were prepared and characterized by IR spectral and scanning electron microscopy (SEM) techniques. The beads were examined for water uptake potential, and he influence of various factors, including chemical composition of the macromolecular matrix, pH, ionic strength, and temperature of the swelling medium, were investigated on the degree of water sorption. The prepared beads were loaded with KNO3, as a model agrochemical, and the release kinetics of KNO3 were studied under varying experimental conditions, as mentioned previously. The release data were analyzed by Fick's equation, and the mechanism of KNO3 release was worked out at different experimental conditions. (C) 2004 Wiley Periodicals, Inc.