Ultrasound techniques for the characterization of liquid-liquid dispersions have previously shown their value and promise, but still require refinement and careful, preferably non-invasive, implementation. Their combination with drop size distribution measurement techniques is also an important area for further development. A new non-invasive implementation has been developed, studied and evaluated in detail, which leads to accurate hold-up fraction measurements (to within -0.0123 units), surpassing that of most previous techniques. The largest error incurred by the effect of the propagation through the vessel wall glass has been shown to be negligible, the same applying to the effect of the propagation across the agitator shaft. Actual experimental dispersed phase hold-up fractions of up to 40% were tested and successfully correlated, in addition to 100% organic phase. (c) 2006 Elsevier B.V. All rights reserved.