A vibration technique for promoting fluid mixing and chemical reaction in a microchannel was proposed, and the effects of the mechanical vibration on mixing and reaction were experimentally examined. The fluids before flowing into a microchannel were oscillated by a small vibrating motor through two tubes connected to the channel. Instantaneous velocity and concentration were measured using micro PIV and LIF techniques, respectively. The results show that fluid mixing and chemical reaction is remarkably promoted by the proposed vibration technique. The mixing rate is well correlated with the maximum rms value of normalized fluid velocity fluctuation in a microchannel. When the basic frequency of the mechanical vibration is low, the fluid motion hardly changes and the mixing and reaction is little enhanced. However, with increasing the frequency, almost complete mixing and reaction can be accomplished at the high frequency more than 90Hz by the proposed technique. (c) 2006 American Institute of Chemical Engineers.