The spray and combustion characteristics of the new bio-fuel candidates, 2,5-dimethylfuran (known as DMF) and 2-methylfuran (known as MF), are examined using optical diagnostic methods. A macroscopic spray characteristics study using high speed imaging has been performed to gain the understanding of the bio-fuels’ spray behavior under various conditions compared to gasoline and isooctane. The droplet sizes of the bio-fuel injections under different operating conditions are also studied using Phase Doppler Particle Analyzer (PDPA). The laminar flame propagation and the turbulent flame propagation for MF and DMF have been benchmarked against isooctane.