n-Decane, n-dodecane, and n-tetradecane have been cracked at very short time on stream on ZSM-5, BETA; and USY zeolites. It is shown that different reaction schemes can be used to explain the initial selectivity values obtained for the different products. In all cases an "uncertainty band" was found which makes it impossible to determine with accuracy the separated contribution of the mono- and bimolecular cracking to the overall cracking. Nevertheless, it has been possible to establish the selectivities for the hydrogen transfer reactions. Finally, the influence of the zeolite structure, chain length, time on stream, and level of conversion, on the product distribution and the extent of the reactions involved has been studied.