In this research, the selective oxidation of benzene to maleic anhydride (MAN) in a fixed-bed reactor was studied. The gas phase catalytic oxidation of benzene was carried out in a laboratory scale fixed bed reactor on the catalysts, which were prepared having two different compositions on silica gel. The effects of temperature, flow rates of benzene and air, and catalyst type on the reaction selectivity were investigated at normal atmospheric pressure. The experiments were performed at the temperature range of 300 degrees C to 375 degrees C, the space-time (W/F-BO) range was from 1*10(6) to 2.5*10(6) g.sec/mole, and the air/benzene weight ratio changes were between 16-51. Experimental results show that the maximum conversion is obtained at 375 degrees C, at the space-time 1.33*10(6) g.s/mol and at the benzene/air mol ratio 41.36 by using first catalyst. According to the experimental results, a difference between catalyst 1 and 2, it could not be seen. MAN conversion was observed for both catalysts and both catalysts are suitable for oxidation of benzene to MAN in a fixed bed reactor.