The progress of microwave-promoted reactions can be monitored by interfacing a Raman spectrometer with a scientific microwave unit. The apparatus is assembled from commercially available components. It is used in this protocol to follow the base-catalyzed reaction of salicylaldehyde with ethylacetoacetate to yield 3-acetylcoumarin. It is possible to watch the reaction spectroscopically in real time, determine when it reaches completion and thus use it as a tool for rapid reaction optimization.