The mechanism and kinetics of methanol oxidation to formaldehyde on an industrial Fe-Cr-Mo catalyst have been investigated using the TAP (temporal analysis of products) reactor. The Mars-van Krevelen redox mechanism of partial oxidation was confirmed. By kinetic isotope experiments, the abstraction of hydrogen from the adsorbed methoxy intermediate was found to be the slow step on the catalyst surface. Water was observed to readsorb strongly on the catalyst, thus explaining the reduced rate of reaction that has been found at high methanol conversions. Weaker readsorption of formaldehyde was observed. The kinetics of the reaction were studied on a fully oxidized and a partially reduced catalyst. On the fully oxidized catalyst, the activation energy for formaldehyde formation was estimated to be 87 kJ/mol. At 360 degrees C the average surface residence time of the adsorbed species in the conversion of methanol to formaldehyde was approximately 40 ms, meaning that the surface reaction rate constant for the main reaction is 25 s(-1). The surface residence time was significantly longer on the partially reduced catalyst, indicating a much slower surface reaction rate constant and emphasizing the importance of oxidation state on the rate of formaldehyde formation.