Vertical columns 1- and 2-m in height were packed with coarse coke particles, and were used as the cold model for a blast furnace. In order to estimate the transient accumulation behavior of fines from the gas phase to the surfaces of the packings, a mixture of gas and fines was injected into the bottom of each packed bed, and the transient discharge rate of fines at the outlet of the column was determined. Fines used in the present experiment were sieved coke particles 75-, 125-, 210- and 375-mu m in diameter. The time required to attain a constant discharge rate decreases with increasing feed rate of fines and gas velocity, but is not greatly affected by the diameter of fines, A mathematical model for the transient discharge rate of fines was proposed assuming a transportation rate of fines to the packing surfaces from the upward stream, and that to the upward stream from the packing surfaces. Values of these parameters are correlated with experimental variables.