A silica support for use in the manufacture of a silica supported
heteropolyacid catalyst for use in producing a carboxylic ester from a
monocarboxylic acid, olefin and water wherein the support is produced by
treating silica-gel granules with steam at a temperature in the range 100
to 300.degree. C. for a period of time in the range 0.1 to 200 hours.