Contact angle measurements were carried out in coal ranks of 32.1 and 32.2/n-alkane film - air bubble - aqueous diacetone solution systems. In these studies n-alkanes in homological series from n-hexane to n-hexadecane and aqueous diacetone alcohol solutions in concentration range from 0 to 10% were used. On the basis of obtained results the adhesion work of aqueous diacetone alcohol solutions to coal surface precovered with n-alkane film was calculated from the modified Young equation. These investigations showed that an increase of n-alkane film thickness causes a decrease of the wettability of low-rank coals as well ob a decrease of the adhesion work of aqueous diacetone alcohol solutions to coal/n-alkane film surface. An increase of the may be also stated, that an increase of the quantity of diacetone alcohol molecules adsorbed on coal surface precovered by a small amount of hydrocarbon causes a decrease of the adhesion work, but when the coal surface is precovered by a big amount of hydrocarbon the adhesion work is increased.