Coaxial airblast atomizers have many applications, including fluidized bed denitration in the nuclear industry and aerospace propulsion. Small droplet sizes at the moderate gas-liquid mass ratios are desirable in these applications. Experimental studies on a novel airblast atomizer, designed to control the droplet size using variations in the dimensions, are reported in this article. The inner tube of the atomizer housing liquid jet terminates in a bluff body face at the exit plane, on which an annular air jet forms a recirculation zone. Jet breakup is induced by the helical instability and shear of the coalesced droplets and liquid film at the bluff body face. Effects of air and liquid jet diameters and swirl of the annular jet on droplet size distributions are studied. Results indicate that the atomizer can be configured to control droplet sizes at the moderate gas-liquid ratios. A striking feature of the atomizer design is its sensitivity to small changes in diameters of liquid and air jets. Atomizer performance is especially sensitive to the air jet diameter. Sauter mean diameter varied by 55% to 128% for nearly 7% variation in air jet diameter. Imparting the swirl to the annular air jet is beneficial only if the air jet diameters are small.