A "stage-1" intercalated film has been made by the ion exchange of pyrrolidinium-functionalized C-60 (C-60(Py)(n+)) into centimeter-wide, micrometer-thick air-dried graphene oxide (G-O) films composed of tens of thousands of layers of stacked/overlapping G-O platelets, denoted [C-60(Py)(n+)]G-O films. Spontaneous intercalation by ion exchange of one layer of C-60(Py)(n+) between adjacent G-O layers expands the interlayer spacing of the films from 0.74 nm to 1.46 nm. The films remain intact in water and various organic solvents, which is likely due to a strong affinity between C-60(Py)(n+) and G-O. Membranes made of the films showed a 6.8 times faster water vapor permeation rate (allowing the vapor to transport through the membrane almost freely) and a 10.5 times faster liquid water permeation rate than G-O membranes. Heating the films at 2000 degrees C under applied pressure or at 2700 degrees C without physical confinement converted them into highly graphitized structures. (C) 2020 Elsevier Ltd. All rights reserved.