Abstract: A method of preparing antimony pentafluoride comprising converting antimony compounds to hydroxonium fluoroantimonates by reaction of the antimony compounds with fluorinating material, such as hydrogen fluoride, in the presence of an oxidizing agent, such as hydrogen peroxide, removing water from the reaction product to concentrate the hydroxonium fluoroantimonates and reacting the hydroxonium fluoroantimonates with carbonyl difluoride to produce antimony pentafluoride. In one embodiment the hydroxonium fluoroantimonates are prepared by recovering the antimony from spent alkylation catalyst comprising SbF.sub.5 deposited on silica. The silica can also be recovered and recycled to produce a remanufactured alkylation catalyst.