A novel method for synthesis of high quality InN nanowires, at temperatures well above their decomposition temperature, has been demonstrated by utilizing controlled oxygen flow in the growth chamber. Detailed structural and chemical analyses indicate that the nanowires consist of pure InN, with no evidence of In2O3 detected by any of the characterization methods. It is proposed that the oxygen, pre-adsorbed on the Au catalyst surface, assists in accelerating the decomposition of NH3 at the growth temperature by providing high concentration of atomic nitrogen to assist in the growth, and prevent decomposition of the InN nanowires, without getting incorporated in them. The proposed role of oxygen is supported by improved material quality at higher oxygen flow rates.