A model of the cubic mesoporous silicate MCM-48, based on the gyroid minimal surface, has been generated by computer simulation. Transmission electron micrographs and X-ray diffraction (XRD) patterns have been recorded for MCM-48 and compared with the images and XRD patterns obtained by modeling. The gyroid minimal surface gives an excellent description for the structure of MCM-48 with the amorphous hydroxylated silicate sited close to the midplane of the surface.