This paper is a preliminary study on Monsang, a hitherto undocumented Trans-Himalayan (or Tibeto-Burman) language (ISO 639-3) of Northeast India. Phonemic analysis for consonants, vowels and tones are discussed and provided. Along with the description, acoustic features are also analysed to show the phonetic realization for each phonemes. Maximally a syllable in Monsang can be CCVVC, and minimally it also allows just a V. Monsang exhibits 25 consonants. There are nine phonemic monophthongs and a diphthong, and two tonemes in limited number of words.