Abstract: Acetylation of samples of lime (Tilia amurensis Rupr.) in the vapor phase with acetic anhydride or thioacetic acid has been carried out using potassium acetate or pyridine as catalyst. All the acetylated wood samples reached a desired level f qualities, with weight gains mounting over 17 percent, the mean anti-shrink efficiency being 74.82 percent as treated with acetic anhydride and 81,44 percent as treated with thioacetic acid.There was a slight difference in dimensional stability resulting from the use of different catalysts in vapor phase acetylations with thioacetic acid. A better result is obtained by using patassium acetate as catalyst rather than pyridine, the difference being significant at a=0.25.As agents of acetylation in vapor phase, thioacetic acid showed a better effect rather than acetic anhydride in the dimensional stability of wood when potassium acetate was used as catalyst, the difference being significant when a approached 0.05 There was an obvious difference in maximum moisture swelling in the samples of the treated wood before and after oven drying. This property shows that a standard method should be set up in the measurement of anti-shrink efficiency.The mean permanent percentage of swelling of the pieces of the treated wood was around 3.02-6.18.The amount of water that the treated wood absorbed in the waterlogged condition decreased by 21.52-28.15 percent on an average. After air drying for half a year, the reduction of water absorptivity of treated wood showed a percentage of 60.57-78.33 as compared with the samples untreated when the R.W.A. was detemined at 21 C and 72 percent of relative humidity.It should be noted that wood should be acetylated to a proper degree to avoid adverse effects.