A new species of the genus Lycodon Boie in Fitzinger is described on the basis of three specimens collected on the Khorat Plateau, Nakhon Ratchasima Province, Thailand. Lycodon gibsonae spec. nov. is superficially similar to L. fasciatus (Anderson), it differs by its much larger size, a higher number of ventral and subcaudal scales, and a lower number of bands on the body, the last three characters presenting no overlap with those of L. fasciatus sensu stricto. The new species seems to be endemic to the Khorat Plateau.