Microreactor technology has been studied as a suitable process to produce chemicals via multicomponent reactions. In this study, efforts were made to produce 3,4-diamino-1H-isochromen-1-ones. Based on a known reaction procedure, using in situ generated HCN, a safe reaction setup was created to avoid the release of the hazardous gas during the process. The 3,4-diamino-1H-isochromen-1-ones were produced continuously in moderate to good yields.