Natural gas combined cycle power plants (NGCC) can be a very attractive technology to utilize natural gas for power production with reduced GHG emissions. In this paper, two power plant systems are presented; the reference case NGCC without CO2 capture and a NGCC plant with carbon capture (pre-combustion technology) using air auto-thermal reformer (ATR) and a sorption enhanced water gas shift (SEWGS) reactor. Both systems have been evaluated by modeling using starting points from the European Benchmark Task Force (EBTF) document. The comparison between the models has been performed with respect to the net plant efficiency (electrical), the gas turbine output, the combined cycle and the net power consumption in the process. The base case NGCC model without carbon capture gives a net plant efficiency of 57.31% which is in line with values reported in literature. For the NGCC model with carbon capture using SEWGS, the net efficiency obtained is 50.94%. The carbon capture ratio is 0.95 with a CO2 stream purity of 99.5%. The efficiency penalty of 6.37% is due to the increase in the power consumption particularly in the gas turbine air compressor and in the CO2 capture and compression unit.