Zeolitic Imidazolate Frameworks (ZIFs) are a sub-class of Metal-Organic Frameworks (MOFs) and one of the best porous materials for the selective uptake of CO2. The room temperature synthesis of a series of Ni2+-doped zeolitic imidazolate framework-67 (Ni@ZIF-67) and their application in selective CO2 adsorption. The structure, morphology and surface area of Ni@ZIF-67 nanocrystals have been examined using spectroscopic and surface analytical techniques. Ni2+-doped ZIF-67 (Ni@ZIF-67), have been synthesised by doping 10, 25, and 75 % of Ni2+ ions into ZIF-67. The metal ion ratios of Ni/Co play a prominent role in controlling the particle size and surface area of Ni@ZIF-67. Moreover, the Ni@ZIF-67 shows enhanced uptake of CO2 (17.12 cm3/g (33.65 mg/g)) compared to ZIF-67 (12.60 cm3/g (24.76 mg/g)). In summary, this work shows a novel and eco-friendly technique for the synthesis of Ni@ZIF-67 for improved uptake of CO2.