A method for isomerizing a 1-olefin-containing organic feedstock having an average carbon number of about 4 to 5, e.g., 1-butene, to convert 1-olefin to 2-olefin at temperatures less than 200.degree. C., with a double bond isomerization catalyst comprising a zeolite sorbing 30 to 55 mg n-hexane at 90.degree. C., 83 torr, and 15 to 40 mg 3-methylpentane at 90.degree. C., 90 torr, per g dry zeolite in the hydrogen form, e.g., ZSM-22, ZSM-23, or ZSM-35. Catalyst aging is minimal despite operation at low temperatures and high pressures.