The method of converting n-butylenes to isobutylene by a skeletal isomrization reaction wherein said reaction is carried out at a temperature of between 300.degree. C. and 650.degree. C., under a pressure of between 0.1 and 100 atmospheres and a space velocity of said n-butylenes of between 0.1 and 40 WHSV using a cagalyst comprising a zeolite binder selected frm the group consisting of alumina, silica, silica-alumina, clay and a combination thereof, said catalyst having a pore size of at least about 4.5 angstroms and the pore size structure is characteried by intersecting 10-member ring and 8-member ring channels.