Experiments on equilibrium adsorption loadings of various probe compounds on 60-200 mesh Illinois #6 coal (PSOC-1539), Adaville #1 coal (PSOC-1544), Wyodak coal (PSOC-1545), and Pitts burgh #8 coal (PSOC-1549) were performed. The probe compounds include 2-methyl-1-pentanol (2M1P), 1-heptanol, benzene, and toluene. Equilibrium adsorption loadings of aromatic compounds such as toluene and benzene on the four chosen coals obey the Langmuir isotherm model up to 100 ppm in concentrations of probe compounds. Equilibrium adsorption loadings of higher aliphatic alcohols such as 2M1P and 1-heptanol on the four chosen coals do not follow both the Langmuir isotherm model and the Freundlich empirical adsorption model. Flotation of the coals, equilibrated with aqueous solutions of 2M1P and l-heptanol, increases linearly with equilibrium adsorption loadings of these probe compounds on the coals. The chosen coals were treated with nitrogen and air at 1 atm and 125-225 degrees C for 24 h. Flotation experiments of the treated coals were conducted at room temperature, using distilled water only as a flotation medium. Flotation of Adaville #1 coal and Wyodak coal treated with nitrogen gas is higher than that of the untreated coals and increases with treatment temperatures. Flotation of Adaville #1 coal treated with air at 125-225 degrees C is not significantly different from that of untreated coal. Flotation of Pittsburgh #8 coal treated with air is lower than that of untreated coal and decreases with treatment temperatures. Flotation of Illinois #6 coal treated with nitrogen only is higher than that of untreated coal. Flotation of Illinois #6 coal treated with nitrogen at 125-175 degrees C increases with treatment temperatures, whereas flotation of Illinois #6 coal treated with nitrogen at 175-225 degrees C decrease’s with treatment temperatures.