Multiple regeneration of Pt-containing reforming catalysts were used to explore basic understanding of the coking process and examine structures in the coke profiles. The coking reactions used in the investigation vary from the slow-coking reaction of cyclohexane dehydrogenation on the one extreme to the fast-coking reaction of methylcyclopentane at the other extreme. Intermediate between these extremes are the reforming of isooctane and n-octane. This choice also affords the opportunity of studying the effect of the two functions of the reforming catalyst for single or multiple reaction products. A coking structure was observed for the slow-coking cyclohexane reaction with accessibility to the pores of the alumina. This structure exhibited three stability states depicting regions where the coke profile is constant with cycle number. The fast-coking reaction of methylcyclopentane reaction also showed two of the states although the coking mechanism was fouling of the pore-mouth. The deactivation profiles were predicted with a model utilizing activity-time data. Deactivation parameters were used to predict the size of the coking molecules formed during the reactions. The values showed that the smallest coke molecules were formed for the cyclohexane reaction.