The objective of this research was to investigate the effects of some impregnation materials and varnishes on the thermal conductivity of oak wood. Ammonium sulfate, borax, boric acid, zinc chloride, diammonium phosphate, and sodium silicate as impregnation chemicals and polyurethane, cellulosic, synthetic, coloured varnishes and cellulosic, synthetic, industrial paints as finishes were used. The wood materials were impregnated by using the vacuum-pressure method. The thermal conductivity test was performed based on the ASTM C 1113-99 hot-wire method. Results showed that the impregnation chemicals increased the thermal conductivity. The highest values were obtained with boric acid and sodium silicate. In addition, the thermal conductivity of painted oak was higher than that of varnished oak. The lowest thermal conductivity of 0.1465 Kcal/mh degrees C was obtained with the oak control. The highest thermal conductivity of 0.1756 Kcal/mh degrees C was obtained when oak was painted with industrial paint and impregnated with boric acid.