The hydroconversion of n-dodecane on Pt/SAPO-11 catalyst with 0.5 wt% Pt, was carried out in a microcatalytic pulse reactor at 523-673 K, hydrogen pressure of 3 bar and hydrocarbon pulses in the 0.5-5 mu l range. Under these conditions, yields of feed isomers as well as cracking products are a function of the total n-dodecane conversion. Primary products are the methylundecanes while multibranched isomers and cracked products are formed in successive reactions. The high selectivities of Pt/SAPO-11 for isomerization of n-dodecane are due to the inhibition of the formation of highly branched (and, hence, relatively bulky) carbocations, which are the precursors for the energetically most favorable type A beta-scissions, inside the pores of SAPO-11.