Silica having an enhanced level of dehydration beyond what can be produced by heating alone is produced by a three step process comprising (1) chlorination, (2) dechlorination, and (c) oxidation. The resulting dehydroxylated silica is a novel composition of matter and is useful as a reinforcing agent in rubber or plastics and as a support for a chromatographic column in addition to being suitable for a catalyst support. Where the dechlorinating agent is hydrogen, a hydrophobic silica composition containing.tbd.Si-H structures and essentially no -OH groups is produced which is suitable for use as a reducing agent, a coupling agent as well as a precursor for the oxidized dehydroxylated silica described above. The resulting composition is particularly suitable as a support for chromium-containing olefin polymerization catalysts.
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