In this work, we present our first 3D in vivo EPR oximetry study using Ox071 spin probe in comparison with Ox063 oximetry. The R2* change with [Ox071] and pO2 was calibrated using standard solutions. In vivo EPR imaging of a mouse tumor was performed on successive days by using either Ox071 or Ox063. The zero gradient signal level of Ox071 was about twice stronger and lasted almost twice longer compared to Ox063. The spin density, and pO2 maps and pO2 histograms of tumor regions marked by co-registration with MRI were similar between Ox063 and Ox071.