The samples of resonance spruce were thermally modified in vacuum at temperatures from 170, 180 and 190 °C, and their mass losses caused by heat treatment were evaluated. All the samples, including the control ones, were exposed to four different air humidities (33, 44, 65 and 88 %) at a constant temperature of 20 °C. Then the adsorption and desorption curves were evaluated. In comparison to control samples, the thermally modified ones exhibited lower equilibrium moisture content at all conditions. It was proved that the characteristics of thermally modified samples are in close correlation with their mass losses. Higher the mass loss was, lower was the equilibrium moisture of modified wood. All samples were coated with 3 different surface coats (2-compound polyurethane and urethane-alkyd varnish, 33.7 % propolis solution in ethanol), and exposed to the same equilibrium process as mentioned above. The mass losses of thermally modified samples have stronger influence on sorption characteristics than surface coatings. The characteristics of cured surface coatings (gloss, flexibility and adhesion) on nonmodified and on modified wood were compared. The coating characteristics studied on thermally modified samples were comparable to those on the control ones.