In the adsorption process, the reaction between adsorbent and adsorbate takes place to form product. After the formation of product, it is important to release the product from the surface of adsorbent to create the free surface again. This process is called desorption. Henceforth, more reacting molecules can be adsorbed.

So desorption is important for a substance which increase the rate of the adsorption process by releasing the product faster.