A laser Doppler Velocimetry (LDV) technique has been developed to simultaneously measure the gas and particulate phase velocities in a high-speed jet plume in a 2D bubbling fluidized bed. The laser, optics, and signal processing filters were configured to eliminate problematic laser-beam intensity fluctuations, which can contaminate Doppler signals in optically dense flows. In order to avoid damaging the optical access windows, the high-speed gas jet was seeded with small ice crystals. LDV bursts from the bed particles and gas tracer ice crystals were simultaneously recorded. The Doppler signals from the tracer crystals and bed particles were differentiated based on their burst intensity and coincidence to yield the particulate and gas phase velocities at a given location within the jet plume. Example gas and particulate phase velocity profiles and the associated measurement uncertainties are presented. (c) 2011 Elsevier B.V. All rights reserved.