Radial velocity profiles due to radial temperature gradients inside a preparative continuous annular chromatograph (P-CAC) are calculated and their influence on the separation performance is studied. A commercially available version of a P-CAC, which can be thermostatted from the inner cylinder, is investigated. The coupled equations for heat transfer and fluid flow are solved with a finite difference method. As an example, the movement of a concentrated and an infinitely diluted aqueous sucrose solution through a cation exchange resin is examined. Calculations are performed for a desired operating temperature of 60 degrees C and different inlet temperatures. The influence of the velocity profiles on the elution profiles is first investigated for the simple case, where only temperature effects occur, and second in combination with mass transfer effects. A comparison with peak broadening in the isothermal case shows that the influence of mass transfer and temperature is of the same magnitude.