The process of bubble dissolution in reactive coatings and the role of benzoin as a degassing agent have been investigated. The gas bubble shrinkage was monitored using a light microscope equipped with a hot stage. In the absence of benzoin, the air bubbles started to shrink very slowly as a result of a diffusion-controlled process. Because of the continuing cross-linking reaction and increase in the viscosity, the bubble shrinkage halted at elevated temperatures. Quite remarkably, we observed that in the presence of benzoin the process of bubble shrinkage was accelerated to such an extent that most air bubbles dissolved before any significant increase in the viscosity occurred. This suggests that benzoin functions by accelerating the rate of bubble shrinkage. To elucidate the mechanism of the action of benzoin in detail, we studied the coating formulations using various techniques. X-ray diffraction in combination with deuterium NMR on labeled benzoin indicated that benzoin is distributed on a molecular level in polyester resin and becomes mobile above the glass transition of the matrix. Mass spectroscopy experiments revealed that benzoin, in its oxidized form (benzil), starts to evaporate above 100 degreesC. As can be expected, the conversion of benzoin to benzil is halted when experiments are carried out under nitrogen. We postulated that the action of benzoin as a degassing agent is related to its ability to oxidize in situ. This claim was substantiated by the results of bubble dissolution experiments using different gases such as oxygen and nitrogen. It was found that in the presence of benzoin oxygen bubbles shrink much faster than air bubbles. On the other hand, the shrinkage of nitrogen bubbles is not affected by benzoin. On the basis of the above results, a two-step mechanism is proposed for the action of benzoin as a degassing agent.