It is a common practice in flotation to compare the action of various reagents on the basis of results of experiments carried out at several concentrations or amounts of reagents, identical for cach reagent used. The same concentrations do not mean, however, the same surface coverages or the same dispersion of gas bubbles in the flotation celI. In this paper, results of flotation of various coals were analysed as a function of coneentration and surface activity of aliphatic alcohols. Coal slimes from the Halemba, Rydultowy, and Pokój Mines were floated. The aIiphatic alcohols used as collecting/frothing agents were n-butanol and n-pentanol, and n-hexanol. It was found that the concentrate yields and ash content in tailings increase with the concentration of these alcohols. Also, at the same bulk concentrations, the longer the hydrocarbon chain of the alcohol molecule, the better the flotation results. The increase in floatability of coals with the length of the hydrocarbon chain in the alcohol molecule is associated with a simultaneous increase in surface activity ofthe homologous series of alcohols. When the processes are compared at the same surface activity (the same surface pressure), the concentrate yields are practically independent of the alcohol used. This shows that the action of aliphatic alcohols in flotation consisted mainly in enlarging the solution-gas interface, and their collecting properties in respect to coal slimes studied were very similar.