base other variations known to the art will suffice where the air treatment is used the catalyst is preferably heated to a temperature of from about 250 u00b0 to 300 u00b0 c during halide deposition organic halides are preferred for treating the catalyst such as carbon tetrachloride trichloroethylene etc as before stated any method of and any halide suitable for depositing the halide on the base is embraced within the practice of this invention catalysts thus constituted are then basically prepared for skeletal isomerization as below described while the thrust of the invention is to branch isomerize n butenes any isomerizable n alkenes may be successfully converted by this invention the olefin feedstock may be pure n alkene or in the preferred aspect additionally contains n alkanes of about the same carbon number as the n alkene to be treated in addition the feed preferably contains a halogenated compound in small amounts i e 50 to 5000 ppm suitable such compounds include the same as used to treat the catalyst as indicated the primary motivation is to skeletally isomerize n butenes and the examples will illustrate the invention with reference to feedstocks containing this type of olefin the preparation of a catalyst for use in the method of this invention is illustrated as follows a catalyst comprising 1 palladium on eta alumina is charged into a reactor air is passed through a moisture trap and then through the reactor while the catalyst is heated to about 260 u00b0 c this step is intended to dry out the catalyst in order to insure that the halide subsequently introduced will be adsorbed onto the alumina this air drying procedure lasts about one hour at a space velocity.