In this study, maceral groups in 15 samples from the central Alborz coal mine of Iran were separated based on the different size fractions of -500 + 150, -150 + 75, -75 + 40, -40 + 25, and -25 mu m. A total of 75 polished sections were prepared, and maceral groups were determined using microscopic studies. For the majority of the samples, vitrinite was concentrated in the fine size fractions, i.e., -40 + 25, and -25 mu m. For the different size fractions of -500 + 150, -150 + 75, -75 + 40, -40 + 25, and -25 mu m, samples with maximum and minimum amounts of vitrinite (minimum and maximum amounts of liptinite, respectively) were used to determine the effect of separation maceral groups based on particle size on coal flotation. The results showed that samples with higher amounts of liptinite (lower amounts of vitrinite) produced a concentrate with higher combustible value and recovery. Liptinite had a positive effect and vitrinite had a negative effect on combustible value and recovery of coal flotation concentrate. It can be concluded that, in coal flotation system, separation the maceral groups by particle size is as important as other established factors. (C) 2012 Elsevier Ltd. All rights reserved.