In this work the effect of incorporating up to 12.8 vol % of light cycle oil (LCO) in the conventional FCC feedstock was studied in a microactivity plant (MAT). The experimental work was carried out at typical operating conditions (reaction temperature of 516 degreesC and catalyst-to-oil ratio of 5, 6, and 7). An equilibrium catalyst taken directly from,tbe circulating inventory of an industrial catalytic cracking plant and real feedstocks were used in this study. A reduction-in conversion, gasoline and LPG; yields, and an increase in dry gas and coke yields were observed with the Increasing amount of LCO in the feed. Gasoline RON also increases as the LCO content is increased in the FCC feedstock, The optimum amount bf LCO in the feed was found to be 7 vol %, which maximizes the valuable product production.