The zero length column (ZLC) technique for measurement of pore diffusivity in chiral adsorbent CHIRALPAK AD with particle size 20 and 50 mu m at temperature of 25 degrees C was used. Due to limited sensitivity of the detectors and higher liquid density, the experimental conditions under which the reliable pore diffusivity measurements can be provided are limited. Simulations have been carried out in order to analyze the effect of the model parameters and to choose the proper experimental conditions. The theoretical model which considers the ZLC cell as a continuous stirred tank has been applied. For both particle sizes, pore diffusivity at temperature of 25 degrees C is 4.0 x 10(-6) cm(2) A and tortuosity 7 was calculated. Good agreement was found between the experimental and simulated desorption curves. (c) 2007 Elsevier B. V. All rights reserved.