A study on n-butane isomerization reaction over persulfated zirconia was performed under atmospheric pressure varying pretreatment gas, butane diluents, concentration of butane, contact time and reaction temperatures. It was found that pretreatment of the catalyst in various atmospheres such as nitrogen, hydrogen and air altered the properties of the catalyst as well as its performance towards n-butane isomerization. Air, as a pretreatment gas enhanced the initial activity of the catalyst; whereas, hydrogen had a negative effect. Among the pretreatment gases used, air and hydrogen were the most and the least deactivating carrier gases, respectively. Increase in conversion with increasing butane concentration, the reaction product distribution, and the induction phenomenon together strongly supported the existence of a surface stabilized C-8(+) species and a bimolecular mechanism of n-butane isomerization reaction.