A new mixing device, suitable to achieve the mixing of reactants undergoing fast chemical reactions, is studied. In the sliding-surface mixing device, the chemical reagents are introduced in a confined mixing zone (CMZ), in which high shearing stresses are created in a very small volume to realize rapid micromixing. A system of parallel competing test reactions was used to characterize the micromixing level in the CMZ as a function of feed flow rate, rotation speed, feed pipe position, and a geometric parameter characterizing the CMZ. The influence of these parameters on micromixing efficiency was studied, and a hydrodynamic model was developed This model successfully predicts micromixing times that were measured at two different flow regimes, two feed points, four recirculation flow rates, three geometric configurations, and various stirrer speeds.