The local velocity of the upward particle motion has been determined in a dense fluidised bed by the means of fibre optical probe. The probe consists of two independent light gates. The particles passing in front of the light gates reflect the light generating sign sequences that have been analysed by computer. From the average time difference of the sign sequences and from the distance of the light gates the local velocity can be calculated. Research has been carried out to compare the particle motion of conventional fluidised beds and fluidised beds equipped with mechanic agitators. We have examined the local velocity of the particles along the height and diameter of the fluidised bed and also as a function of the fluidisation gas velocity and the number of rotations of the agitator. We have come to the conclusion that the mean velocity is in dose correlation with the void fraction of the dense fluidised bed and depends on the bed height and the number of rotations and mainly on the fluidisation gas velocity. Using a mechanical agitator the mean velocity of the particles has become higher and the particle motion has become more even.