The present invention is a method for preparing stable HBOC solutions. Specifically, the method comprises the steps of deoxygenating a PEG-Hb conjugate and adding one or more antioxidants during or following the deoxygenating step to form a stabilized PEG-Hb conjugate. The Hb in the PEG-Hb conjugate is not crosslinked and the stabilized PEG-Hb conjugate has a p50 less than that of native SFH from the same animal source when measured under the same conditions. Specifically, the p50 is 6±2 mmHg or less than 10 mmHg.