The extinct Pyu language was spoken during the first millennium CE and the early centuries of the second millennium CE in what is now Upper Burma. It has been classified as Sino-Tibetan on the basis of basic vocabulary, but its precise position within the family remains unknown. It survives in inscriptions in an Indic script. In this study, the first of its kind, I begin to reconstruct Pyu phonology on the basis of spellings in those inscriptions. I propose that Pyu was a sesquisyllabic language with 7 preinitials and 43 or 44 initials.