Chitosan coatings prominently improved both the gloss and oxygen barrier properties of paper. The gloss value in the machine direction was increased as a function of added chitosan. An oxygen-permeability value of 1.1 CM3/m(2) d was obtained when 6.9 g/m(2) chitosan was applied to 80 g/m(2) copy paper. In addition, the effects on the mechanical properties were positive, but not significant. The water-vapor permeability of the paper increased as a result of the chitosan coating. Chitosan dissolved in 1.6, 3.2, and 6.4% lactic acid showed antimicrobial activity against Bacillus subtilis, whereas acetic and propionic acids (1.6, 3.2, and 6.4%) did not produce any notable activity. Nisin (0.08 g/L) did not enhance the antimicrobial activity of coatings prepared from chitosan dissolved in different acids. (C) 2004 Wiley Periodicals, Inc.