Cryogenic separation technologies for CO2 capture have been proven promising due to a less negative environmental impact, and their capabilities to handle high CO2 content natural gas. Design and operation of a cryogenic CO2 capture process require appropriate phase behaviour study of the natural gas components and optimization due to high cooling duty. In this work, Aspen HYSYS simulator along with Peng Robinson property package was used for the thermodynamic phase study of the natural gas. A dedicated experimental setup comprises of a cryogenic packed bed along with an efficient control system was designed and fabricated for the separation study. High CO2 content natural gas with 75 and 90 mol CO2 was used as a feed gas. The research work shows three optimum conditions for the mixture having 75 CO2, i.e. at 4, 10 and 14 bar pressure and at �139.8, �132.6 and �121.3 °C temperature, respectively. For the feed with 90 CO2, the obtained optimized pressure and temperature were 5, 8, and 9 bar, at �121.4, �110.5 and �105.8 °C, respectively. Both of the predicted showed an excellent agreement with the experimental thermodynamic data. This research work is promising to overcome the energy crisis by utilizing the contaminated natural gas reservoirs and can reduce carbon footprint by capturing CO2 at the source. © 2019 Elsevier Ltd