Injection of fuel containing CO2 has potential to reduce NOx and soot emissions in a diesel engine. The gas is dissolved into fuel prior to injection. This paper presents an experimental study on the spray characteristics of fuel containing CO2 as measured by phase Doppler anemometry. Experiments were performed under atmospheric conditions on diesel hole-type nozzles at constant injection pressure. Effects of CO2 concentration in diesel fuel on the spray pattern, droplet size, and velocity were measured. Experimental results show that fuel atomization will improve greatly when the concentration of dissolved CO2 in the fuel exceeds the critical value. The axial and radial velocities of the fuel spray containing CO2 is larger than that of conventional diesel fuel spray near the nozzle exit due to explosive flashing phenomena. Downstream of the spray, the radial velocity and droplet size of fuel containing CO2 is much more uniform and smaller than that of pure diesel spray. It is attributed to the greatly enhanced liquid-gas mixing resulting from flash separation of CO2 from the liquid. New insight into the atomization of fuel containing CO2 was obtained and a possible mechanism to explain the phenomena was proposed.