The use of electrical resistance tomography to monitor the extent of solids deposited during slurry conveying in a horizontal pipe is demonstrated. The method involves placing 16 electrodes around the inner bore of the pipe section, from which a two-dimensional electrical conductivity map within the cross-section can be deduced. The sensitivity of the method is quantified for static and flowing conditions. Variations in the cross-sectional conductivity and the hence solids concentration are reported as a function of the flow velocity and solids loading. Prospects for the implementation of the measurement method in industrial plant are discussed.