The kinetics of methanol oxidation to formaldehyde was studied over an iron molybdenum oxide catalyst in a continuous flow reactor with external recycling at temperatures of 200–300°C. The kinetics of the reaction were well described by a power law rate expression of the formr=kPCH 3OH x PO 2 y PH 20 z , wherex=0.94±0.06,y=0.10±0.05, andz=−0.45±0.07. The measured activation energy was 98±6 kJ/mol. When product inhibition by water vapor is not taken into account in such a power law kinetic rate expression, the apparent reaction orders in methanol and oxygen,x ′ andy ′ , and the activation energyE ′ are all lower than their true values:x ′ =(1−δ)x,y ′ =(1−δ)y, andE ′ =(1−δ)E, where δ=−z/(1−z). Methanol chemisorbs dissociatively to form methoxy and hydroxyl groups, and the rate-determining step is the decomposition of the methoxy intermediate. Product inhibition occurs through kinetic coupling, whereby water vapor chemisorbs dissociatively to form hydroxyl groups, which serve to reduce the steady state concentration of methoxy groups on the catalyst surface by reacting with them to reform methanol.