A description of a computer program giving the path of a percolating smooth spherical particle through a three‐dimensional cluster of stationary spheres, under the influence of a gravitational field is presented.The history of the moving particle starting with an arbitrary velocity and position is followed. The coefficient of restitution for the spheres is an input variable. When the gravitational force approaches zero and the coefficient of restitution is unity, the computer program can also be utilized for the treatment of radiative heat transfer and for Knudsen diffusion in packed beds.