Non-uniform pore geometries often lead to differences in adsorption and desorption pathways within a capillary.  This deviation in the two is called a hysteresis and is characteristic of many path dependent processes.  For example, if a capillary's radius increases sharply, then capillary condensation (adsorption) will cease until an equilibrium vapor pressure is reached which satisfies the larger pore radius.  However, during evaporation (desorption), liquid will remain filled to the larger pore radius until an equilibrium vapor pressure that satisfies the smaller pore radius is reached.  The resulting plot of adsorbed volume versus relative humidity yields a hysteresis "loop."  This loop is seen in all hysteresis governed processes and gives direct meaning the term "path dependent."  The concept of hysteresis was explained indirectly in the curvature section of this article; however, here we are speaking in terms of a single capillary instead of a distribution of random pore sizes.
Hysteresis in capillary condensation has been shown to be minimized at higher temperatures.