Date pits were Used to produce a highly porous activated carbon. The resulting date-pit activated carbon was used in a volumetric adsorption apparatus to measure the vapor-phase adsorption and desorption of nitrogen, methane, ethane, and ethylene over a wide range of pressure and at temperatures of (30, 45, and 60) degrees C. Being characterized with a relatively high Surface area, the synthesized date-pit activated carbon exhibited a satisfactory capacity for adsorbing the Various tested gases. However, the desorption of these gases exhibited a hysteresis phenomenon, especially at low temperatures. A Langmuir type model was proposed for fitting both the adsorption and the desorption data with hysteresis, and the corresponding isosteric heats of adsorption and desorption were estimated and compared.