Abstract: The present technology includes a system and method for monitoring a donor organ tissue using Raman spectroscopy. The technology enables real-time quantification of the mitochondrial redox state in the tissue sample taken from an organ intended for transplant using a compact device. The system is based on resonance Raman spectroscopy which can quantify a mitochondrial redox state in tissues using a Resonance Raman Reduced Mitochondrial Ratio. The mitochondrial redox state of the tissue sample acts as a marker of tissue function and may distinguish healthy versus damaged tissue. Moreover, these measures may correlate with transplantation outcomes.