The diffusion of cyclohexane and several alkylcyclohexanes in silicalite was studied using a simultaneous thermal analyzer. This apparatus allowed for the determination of heats of sorption and diffusion coefficients. Zero length chromatography was also used to determine diffusivities of some of the adsorbates. The trend in diffusion rates observed was trans-1,4-dimethylcyclohexane >> methylcyclohexane > cyclohexane > ethylcyclohexane, cis-1,4-dimethylcyclohexane. This is in qualitative agreement with the previous results of Chon and Park. A comprehensive interpretation of the experimental results was developed, using the basic qualitative arguments of transition state theory. The fast diffusion of trans-1,4-dimethylcyclohexane is associated with a relatively low energy barrier for channel crossing. The transition entropy for diffusion appears to be the reason for the more rapid diffusion of methylcyclohexane relative to cyclohexane.