The dry based coating of core particles with soluble powder dispersed inside an impermeable layer of biodegradable wax was performed to control the release rate of core material. The mathematical model was developed to describe the release profiles by diffusion of core material through the percolation paths formed with soluble powder inside the coating layer. Then, the effective diffusivity was estimated by a random walk model. The experimental release profiles for the urea core particles coated with urea powder dispersed inside a lauric acid layer were quantitatively compared with simulated ones for different volume fractions of soluble powder and thickness of the coating layer. As a result, the low release rate of core material was proven to be obtained with low volume fraction of soluble powder dispersed in the thick coating layer.