The simulated moving bed (SMB) technology has shown great potential for fine chemical separations, particularly for the resolution of the enantiomers of chiral compounds. Further improvements of separation performance are expected when each section of the unit is optimized independently by applying a gradient of temperature, pressure, or solvent composition along the unit. The aim of this work is to extend the design criteria for nonlinear SMBs to the case where a temperature gradient mode is adopted. It is shown how beneficial this can be in terms of productivity and solvent consumption. Finally, the temperature transient in the columns is studied. It is shown that temperature changes in the column of the unit yield a constraint on the maximum fluid velocity. This is analogous to the constraints due to column efficiency and packing stability requirements. The results show that the temperature gradient operation of an SMB unit is feasible and may have significant advantages over the traditional isothermal mode.