In the current research, mixed matrix membranes (MMMs) comprising of 5, 10, 15 and 20 wt of zeolitic imidazolate framework-8 (ZIF-8) were incorporated into 6FDA-durene polyimide phase. The effect of ZIF-8 loading on the membrane performance of CO2 and CH4 separation was investigated. The excellent compatibility and good distribution of ZIF-8 nanofiller in 6FDA-durene polyimide phase even at higher ZIF-8 loading up to 20 wt has resulted in the increment of CO2 permeability and CO2/CH4 selectivity compared to pure membrane. In this work, 6FDA-durene loaded with 10 wt ZIF-8 demonstrated impressive CO2 permeability of 1426.75 Barrer with CO2/CH4 selectivity of 28.70, which successfully surpassed the Robeson 2008 upper bound. © 2016 The Authors.