A method for sanitizing and disinfecting a surface using an aqueous solution of chitosan. The aqueous solution is heated to convert the aqueous solution to a steam vapor containing chitosan. The surface is treated with the steam, thereby disinfecting the surface and simultaneously depositing the chitosan from the steam onto the surface. The steam will also penetrate porous surfaces. An antimicrobial film of chitosan is thereby formed on the surface. The steam vapor sterilizes the surface and the chitosan film inhibits growth of bacteria and other microbes on the surface for several months. The steam containing the chitosan can be generated from an aqueous solution of chitosan heated in standard commercial and home-use steam generators. This chitosan vapor steam treatment of surfaces can be used on any hard surface or soft surface.
