Leptopelis millsoni is a species of frog in the family Arthroleptidae. It is found in southeastern Nigeria, Cameroon, the Central African Republic, Equatorial Guinea, Gabon, the Republic of the Congo, the eastern Democratic Republic of the Congo, and northwestern Angola. Common names Niger forest treefrog (perhaps referring to the mouth of the Niger River, its type locality.) and Millson's Tree Frog have been coined for it. There is a need of taxonomic revision of this taxon.
The specific name millsoni refers to Mr. Alvan Millson, assistant colonial secretary in Lagos and the collector the two female syntypes.
Adult males measure 40–49 mm (1.6–1.9 in) and females 74–87 mm (2.9–3.4 in) in snout–vent length. The dorsum is brown, with darker transverse bars, or green. The tibia has 4–5 bars, and the feet are fully webbed. The iris is rusty red. The tympanum is rather large.
The male advertisement call consists of single calls and has a "peculiar" acoustic quality. The call is similar to the call of Leptopelis notatus, and very similar to that of Leptopelis macrotis. However, the similarity of calls was refuted by Rödel and colleagues.