The kinematics of hand movement have been reported to be encoded in neural activities recorded at the primary motor cortex accompanying or immediately preceding the movement. In our earlier study, we demonstrated that the speed of imagined hand movements can be represented in the noninvasive EEG recordings and continuously decoded. In the present work, we aimed to systematically examine the spectral-temporal dynamics of imagination-related speed embedded in multiple frequency bands of EEG activity, including the alpha, beta and gamma bands and search for the optimal speed decoding for movement imagination.