In froth flotation, liquid recovery is strongly linked to separation performance. In addition to determining its structure, the distribution of liquid within froth affects the recovery of entrained material to the concentrate. Despite its importance, measurements of the liquid content of froths are rare. Most existing measurements are intrusive, only provide low spatial resolution, or rely on small samples of foam. This work demonstrates the use of positron emission tomography (PET) to measure the distribution of liquid in a 2D overflowing foam. Results show a liquid fraction of 0.36 at the base of the foam column decreasing to a liquid fraction of 0.03 at the foam surface. This shows the potential to use PET studies to measure 3D foam structures and to validate simulations of flotation froths. (C) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.