Obo Manobo is a language of the Central Manobo subgroup of Philippine languages. It is spoken by an undetermined number of people on the island of Mindanao, more specifically on the north and west slopes of Mount Apo on the boundary between Davao del Sur and North Cotabato. The study is aimed only to define the actual phonology and morphophonemics of the Obo Manobo language, thus any data known to be borrowed have been consciously excluded except for comparative purposes.