Formaldehyde, as a valuable compound, has been widely used in chemical processes and is usually produced through the catalytic oxidization of methanol in a fixed bed reactor. In the present work, this reaction has been studied in a fluidized bed reactor. For this purpose, a stainless steel fluidized bed reactor , which has the capability of controlling the temperature and flow rate of the streams, has been employed. The effects of different operating variables on the performance of the above-mentioned reactor are studied. The results are compared with the two and three phase models