In the last decade, photoacoustic techniques have been used extensively to acquire label free oxygen saturation (SO2) images of blood vessels both in vivo and ex vivo. Recent advances in photoacoustic microscopy have pushed the in vivo resolution limit of photoacoustic SO2 mapping to that of a single cell. In this work, we use a photoacoustic microscope equipped with a 0.9 GHz ultrasound transducer and a fiber coupled 532 nm Nd:YAG laser source to generate sub-cellular resolution SO2 maps of single red blood cells (RBC) ex vivo. Stimulated Raman scattering (SRS) within the optical fiber produces secondary peaks in the laser output spectrum, which can be isolated as discrete photoacoustic excitation sources by using optical bandpass filters. Photoacoustic images acquired at the different excitation wavelengths are co-registered, and a local SO2 map for the RBC is created. Untreated RBCs, as well as RBCs that had been chemically deoxygenated with sodium dithionite were imaged with the system. The resultant SO2 maps show a high percentage of SO2 through out the untreated cell, as well as localized pockets of both high and low SO2 in the treated cell. For the untreated cell, the mean and median SO2 values were 72 and 73%, respectively, while for the treated cell they were 56% and 57%. This multispectral PA technique has potential applications in assessing chromophore distribution and oxygen transfer kinetics at the sub-cellular level.