Char oxidation experiments were performed with a sub-bituminous roto-middle coal in the Drop Tube Furnace (DTF) at atmospheric pressure condition. While temperatures varied between 900, 1100, 1400 $^{circ}C$, particle size, mass, particle temperature, and CO/$CO_2$ concentration were obtained to be used for kinetic analysis of the char oxidation. This study addresses several different methods to analyze the char consumption rate, which are classified as energy balance method, ash-traced mass method, flue-gas based method, and particle size based method. The char consumption rate obtained with such methods was compared with the results of Monson et al.$^{(24)}$ While there are some differences between them because of differences in experimental apparatus and parameters to be measured, the kinetic results seems to be reasonable enough to be incorporated in a numerical modeling of coal combustion.