The diffusion characteristics of several solutes into the Ca-alginate gel beads have been investigated experimentally in a well mixed batch reactor. The experimental variables were concentration of CaCl₂(0.05M, 0.5M), temperature(30-50℃), concentration of Na-alginate (1.5-4wt%), and the kind of solutes with different molecular weight such as glucose, xylose,, maltose, and lactose, respectively. The effective diffusion coefficient was determined by measuring solute concentration in the solution with time. It was found from this experiment that the values of the effective diffusion coefficient of glucose and xylose were not affected by the concentrations of Na-alginate and CaCl₂, but those of maltose and lactose were very much affected by the concentration of Na-alginate, especially in the rage of 2-3%. The effect of temperature on the diffusion of glucose and xylose with relatively small molecular weight could be neglected.