Graphene oxide (GO) laminate membranes of controlled interlayer spacing were synthesized for the investigation in H-2/CO2 separation. The interlayer distance of GO flakes was tuned by crosslinking and intercalation of La3+ or Co2+ cations between GO layers. Investigation via field-emission scanning electron microscope showed that a continuous selective layer was present in the GO-La3+, GO-Co2+ and GO membranes. Gas permeation results revealed that the GO-La3+ membrane had better H-2 permeability and H-2/CO2 selectivity than the other membranes, due to an increase in d-spacing between the GO layers and restricted defect formation in the GO laminate membranes. In addition, the H-2/CO2 separation performance of GO-La3+ membrane was found to be close to the upper bound limit of conventional polymer membranes established in 2008.