A process for the preparation of an antimicrobial coating solution is described. The process comprises the steps of: (i) mixing a chelating agent with titanium alkoxide and fluoroacetic acid; and (ii) adding an aqueous solution to the mixture from step (i). The antimicrobial coating described is visible light activated. The coating is applied to surfaces and then heat treated to form a transparent layer on the surface. This is particularly advantageous where the surface is glass.