STM, one of the few surface techniques not restricted to vacuum, can in principle obtain atomically resolved images of catalyst surfaces under the high pressure/high temperature conditions of industrial catalytic reactions. Using STM under these "operando" conditions one may thus obtain the most direct access to fundamental questions of catalysis research, such as about the structure of the active surface, the distribution of adsorbed molecules in the reacting layer, and the operation of active sites. However, progress has so far been limited, a result of many practical problems. Here I will present operando STM data of the Fischer-Tropsch synthesis, a large-scale industrial process by which syngas, a mixture of CO and H2, reacts to give hydrocarbons for liquid fuels. Using a Co(0001) single crystal model catalyst, production of hydrocarbon molecules was detected under conditions approaching those in the actual process. At the same time atomic resolution was achieved by STM. The data are in surprising conflict with existing models of this reaction. I will also discuss experimental problems connected with such experiments and our current efforts to overcome these difficulties.