The fixed-bed microreactor used for carrying out transient kinetic experiments in the temporal analysis of products (TAP-1) reactor was significantly modified, thus allowing investigations with strongly adsorbing gases. The design of this microreactor minimized side reactions and adsorption on the reactor walls in order to perform catalytic measurements over low surface area catalysts using very small pulses under high vacuum conditions. These enhancements were achieved by fitting an inert quartz insert into a metallic reactor body which was specially designed for isothermal operation. Furthermore, the gas feed system was rebuilt using glass-lined heated tubing allowing the calibration of strongly adsorbing gases (e.g., methanol and formaldehyde). The modified TAP-1 microreactor was used to study the kinetics of methanol oxidation to formaldehyde over an electrolytically prepared silver catalyst. The distinct modification of the microreactor and the feed system allowed a quantitative analysis of the experiments.