An autoxidisable architectural coating composition suitable for application to surfaces found in and around buildings at ambient temperatures and in natural daylight wherein surface autoxidation of the composition is promoted by a combination of low concentrations of metal ions (especially manganese or vanadium) and 2,2-dimethoxy-1,2-diphenylethan-1-one as photoinitiator. The composition avoids the need to use more than trace amounts cobalt ions which are rumoured to be carcinogenic yet achieves adequately fast rates of autoxidation. Preferably the use of cobalt is avoided altogether. The use of the low concentrations of the other metal ions reduces discoloration of the compositions often to levels below what is achieved using conventional cobalt promoters. Also a modification in which surface autoxidation is promoted by a combination of 2,2-dimethoxy-1,2-diphenylethan-1-one and trace amounts of cobalt ions in the absence of other surface autoxidation promoting metal ions. Finally, a method for applying the autoxidisable coatings to surfaces under ambient temperatures in which they are subject to natural daylight or similar low energy irradiation is disclosed.