With 70 named species and multiple morphologically cryptic lineages, the genus Hipposideros is a diverse and taxonomically contentious group of insectivorous bats in the Old World tropics. Half of the named species and most of the cryptic diversity in Hipposideros are concentrated in the bicolor species group. Here we resolve the taxonomic status of Hipposideros bicolor (Temminck, 1834), the species group's namesake. Two morphologically cryptic but acoustically and genetically distinct lineages of H. bicolor co-occur in peninsular Malaysia and Thailand. Pending taxonomic revision, these lineages were named according to the average frequency of maximum energy of echolocation calls of populations in central peninsular Malaysia, H. bicolor-131 and H. bicolor-142. To determine the taxonomic status of the two lineages we measured cranial characters from all available type specimens in the H. bicolor species group, and collected morphometric, acoustic and mitochondrial DNA sequence data for H. bicolor-131, H. bicolor-142, and closely related lineages, from multiple localities on the Malay peninsula and Borneo. Consistent with prior studies, acoustic and genetic analyses strongly support species status for H. bicolor-131 and H. bicolor-142. We find subtle but significant differences in cranial characters, including a longer skull and longer upper and lower tooth rows in H. bicolor-131 relative to H. bicolor-142. Most importantly, inclusion of cranial measurements for type specimens in the H. bicolor species group indicates that H. bicolor-131 should retain the species name, while H. bicolor-142 is distinct from all previously named species. We therefore provide a complete description for this new species of bat from Southeast Asia, Hipposideros kunzi sp. nov.