In this project, the selective oxidation of benzene to maleic anhydride (MAN) was studied. Gas phase catalytic oxidation of benzene was carried out in a laboratory scale fluidized bed reactor on six different types of catalysts,. which have different compositions. Effects of temperature, flow rates of benzene and air and catalyst type on the reaction selectivity were investigated at atmospheric pressure. The experiments were performed over a temperature range of 325 to 400 degrees C, a space-time (W/F-AO) range from 11.28 x 10(5) to 31.9 x 10(5) g s mol(-1), and benzene/ air mole ratio changes between 0.0109 and 0.0477. It was seen that conversion of benzene to MAN increased with increasing temperature for the catalysts supported by silica gel, aluminum oxide and titanium oxide. From the results it was found that conversion increased with increasing flow rate of air. When the comparison of the catalysts were made, it could be said that catalysts supported by silica gel showed higher MAN conversions. So it can be concluded that catalysts supported by silica gel were more suitable catalysts for benzene oxidation to MAN in a fluidized bed reactor.