An experimental study into the production of fine drops of water by twin-fluid atomisation has been carried out using two types of atomiser; an internal mixing type atomiser and a novel type of prefilming ah-blast atomiser. The internal mixing type atomiser produced water sprays with volume median drop diameters as low as 10 mu m with air to water mass flow ratios less that unity. A simple novel design of prefilming atomiser achieved comparable performance using air pressures below 10 bar. Semi-empirical correlations for volume median drop diameter with atomiser geometry and operating conditions are proposed for both kinds of atomiser. An experimental study of the pressure drop for two-phase flow across a capillary has also been conducted and results are compared with theoretical predictions.