In this study, an iso-reticular metal-organic framework-3(IRMOF-3) exhibiting microporosity was synthesized from organic linker 2-amino terephthalic acid and salt zinc nitrate hexahydrate (Zn-(NO3)2.6H2O) via catalyst-free, solution-based direct mixing technique. Three samples of IRMOF-3 were post-synthetically functionalized with aminomethyl propanol (AMP) with three different concentrations of 25 wt, 50 wt and 75 wt to produce AMP@IRMOF-3. The structural and texture properties of AMP@IRMOF-3 were studied by FESEM, FTIR, pore size distribution, powder XRD, TGA/DTG, N2 adsorption-desorption isotherms, their selective CO2/CH4 adsorption behaviour over various temperatures (298.15 K, 323.15 K, and 348.15 K). The results showed an enhancement in CO2 adsorption capacity from 1.39 mmol/g to 3.90 mmol/g due to successful incorporation of CO2 philic functionalities. Furthermore, the adsorption isotherms were studied by applying Langmuir, Freundlich, Langmuir-Freundlich, and Toth isotherm models. The isotherms study revealed the unfavourable adsorption behaviour with an increase in AMP loadings with a homogenous system. © 2019 Elsevier B.V.