The changes in RON and liquid yield during the hydroconversion of an n-heptane-benzene-toluene mixture were evaluated in a continuous high-pressure flow reactor using HZSM5(x)-alumina catalysts with variable contents of zeolite. The results from these experiments were compared with those obtained with a real fluid catalytic cracking (FCC) hydrotreated gasoline as the feedstock. An increase in the zeolite concentration altered the acid properties of the catalysts that showed a gradual increase in the intensity of the 3612 cm(-1) IR band, associated with the internal strong Bronsted acid sites of the zeolite. The hydroconversion results;show that increasing the zeolite content in the catalyst leads to a gradual increase in both the RON number of the liquid product and the amount of light hydrocarbons (less than or equal toC(4)), promoted mainly by secondary cracking and dealkylation reactions. Because of this opposite trend df RON and liquid yield, zeolite contents higher than 10 wt % led to an almost constant barrel-octane (RON x fractional liquid yield). The catalytic experiments:with the synthetic mixture as the feedstock show that the main reactivity is associated with the cracking of n-heptane and with alkylation bf the aromatics by olefins produced during n-heptane cracking. Additionally, other reaction pathways that lead to the production of small amounts of n-paraffins (other than n-heptane), isoparaffins, cycloparaffins, and, to a lesser extent, olefins are observed. The main reaction pathways,leading to higher RON with the hydrotreated FCC gasoline as the feedstock seem to be similar to those observed with the synthetic mixture.