Conversions of cyclohexane and cyclohexane mixtures with 2-methylthiophene (5000 ppm S) and pyrrole (500 ppm N) over dual-zeolite cracking catalysts have been studied. The catalysts have been synthesized using zeolites Y in the HREE form and ZSM-5 modified with phosphorus. The effect of conditions (temperature in a range of 510-630 degrees C, dilution ratio of the reaction medium with an inert gas up to 2 : 1 mol/mol) on the cracking product composition has been studied. It has been shown that an increase in temperature and the dilution ratio of the reaction medium contributes to an increase in the light olefin yield. The highest yield of C-2-C-4 olefins (40 wt %) has been achieved over a catalyst with an Y : ZSM-5 zeolite ratio of 1 : 3. The presence of sulfur and nitrogen compounds leads to a decrease in the feedstock conversion and an increase in the light olefin selectivity.