The mixing of a fuel particle in a fluid-dynamically down-scaled bubbling fluidised bed was studied using magnetic particle tracking. Both the resulting steady-state fuel distributions and the underlying mixing dynamics (fuel velocity field) were investigated. The experimental set-up applied resembles the mixing of an anthracite coal particle in a bed with a cross-section of 0.85 x 0.85 m(2) operated at 900 degrees C with fluidisation velocities in the range of 0.16-0.45 m/s and bed heights in the range of 0.25-035 m. Four different gas distributors with variable pressure drops and orifice configurations were investigated. For the cases studied, 7.5 min of sampling time at a sampling frequency of 20 Hz was found to be sufficient to resolve the spatial distribution of the tracer. However, to provide a reliable estimate of the mixing dynamics, a sampling frequency of at least 100 Hz was required, together with a sampling time of approximately 20 s. Results on axial mixing showed improved mixing with increasing fluidisation velocity and bed height. The lateral dispersion coefficients were in the order of 10(-3)-10(-2) m(2)/s (on an up-scaled basis), increased with fluidisation velocity, and were only moderately influenced by the configuration of the gas distributor. (C) 2017 Elsevier B.V. All rights reserved.