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 chelating acid may be a carboxylic acid selected from formic acid, propionic acid, butanoic acid and acetic acid. A metal precursor, such as copper (II) nitrate pentahemihydrate may be dissolved within the aqueous solution prior to the step of adding to the mixture of step (i). The exemplified coating solution comprises titanium isopropoxide, trifluoroacetic acid, glacial acetic acid, deionised water and copper (II) nitrate pentahemihydrate. 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.
