Particle size distribution is an important parameter in flotation process, which affects the floatability and therefore the flotation kinetics. This study aims to investigate the effects of particle size distribution on flotation kinetics of bituminous coal. For this purpose, a series of batch flotation experiments were conducted in rougher stage, and concentrates were collected in different time periods. Then particle size distribution for each concentrate was determined. Five flotation kinetic models were applied for the modeling of data obtained from the flotation tests using MATLAB (Matrix Laboratory) software. The relationship between flotation rate constant, maximum combustible recovery and particle size were studied. The results show that the maximum flotation combustible recovery and flotation rate are obtained with an intermediate particle size (-250 +106 μm). Results of flotation tests fitted well to all five kinetic models. It is found that the first - order model with rectangular distribution of floatability, provides the best fit to the experimental data obtained from the flotation processes among the tested models.