Distillation process is one of the robust, reliable and conventional methods for direct separation method that are widely used in various industries and chemical applications. In fact, more than 90 percent of the separation units applied the distillation process. When the feed of the separation units is gas, the temperature of the system should reduce to synchronize the presence of the two phases. Hence, this process is called cryogenic distillation when the temperature is lower than 120 K. Since this process occurred in the extremely low temperature, specific packings are used. Meanwhile, the structured packing is preferred in comparison with random packing. This type of packing has significant characteristics such as specific material type, low pressure drop, low HETP and high specific surface area. In this research, structured packing is used for separation of air in cryogenic distillation. In the first step, a knowledge of construction of structured packing is obtained. In this regard, an industrial popular structured packing (sulzer-BX300) is chosen as a main model, and other initial packing are constructed based on this model. After a comprehensive studies and several construction process, a structured packing with a specific surface area of 860 m 2 m -3 are designed and fabricated. The main hydrodynamic characteristics and separation capability of this constructed structured packing are determined via standard examinations and the required data are obtained. Our findings show that our structured packings has low pressure drop in comparison to Dixon-1/4 with similar specific surface area while they have the same HETP. In this regard, four distinct models with constant specific surface area (1300 m 2 m -3 ) and different corrugation angle (30 o , 45 o , 60 o and 75 o ) are designed and fabricated. In the followings, the hydrodynamic behavior and separation performance of these packings are investigated, and it is found that reducing corrugation angle of structured packing from 75 to 30 decreases the dry and wet pressure drop 165 % and 300 %, respectively. In addition, the HETP reduced 30 % when the angle is decreased. According to analysis of two main parameters of capacity and separation efficiency, it is found that the corrugation angle of 45 o shows the efficient performance. After a long studies, structured packings with specific surface area of 2100 m 2 m -3 is designed and fabricated. Our experimental investigations show that our structured packings has low pressure drop in comparison to Dixon-1/8 with similar specific surface area while they have the same HETP. This structured packings is used for gas separation in cryogenic distillation column. The experimental findings confirm that PACK-2100 is recommended for cryogenic distillation system for gas and isotope separation. Then, Computational Fluid Dynamic is applied to simulate the flow feature and determined the main factors of this device. The results of the numerical simulation contains dry and wet pressure drop, liquid hold up, concentration distribution in PACK-2100. Three dimensional model of the PACK-2100 is used to simulate a single phase air flow. Initially, the result are compared with experimental data. The comparison of dry pressure drop show a good agreement with experimental data and subtle deficiency (about 22%) is observed. In addition, 2D model is used for investigation of the two-phase flow in the structured packing. The comparison of the experimental and numerical shows about 12% errors in the wet pressure drop. The liquid hold-up inside the structured packing is determined with the present model. Our simulation showed that the liquid hold-up of the fabricated structured packing is approximately 12% to 35% (according to F-factor) which are significantly high among the current commercial packings. The comparison of the experimental and numerical shows about 9% errors in the liquid hold up. Three dimensional model of the PACK-2100 is used to simulate two phase methanol and isopropanol flow for analyzing of mass transfer efficiency. Our results of HETP mass transfer inside structured packings present a good agreement with experimental data. According to the hydrodynamic behavior and mass transfer efficiency of the fabricated structured packings, the designed structured packing has significantly high efficiency rather than conventional random packings that are used for the separation of special purpose (system with highly low separation coefficient). Moreover, the numerical simulation confirms the results of experimental data.