The present invention is method comprising the steps of a) contacting 4-hydroxyphenone and a salt thereof with propylene oxide in a reactor heated to a temperature in the range of from 100° C. to 200° C. to form a poly(propylene oxide)-benzophenone intermediate; then b) contacting the intermediate with ethylene oxide in the heated reactor to form an alkoxylated benzophenone substituted with propylene oxide groups and ethylene oxide groups. The method of the present invention is useful for preparing a non-volatile alkoxylated benzophenone photoinitiator that gives long lasting gloss retention in an exterior architectural coating.