In recent times, composites of graphene are being produced for purposes such as electrodes and gas sensors among others. The synthesis of graphene composites was done via various methods available. Loading copper on graphene like every other transition metal to obtain composite with wide band gap has not been harnessed as such for the similar purposes. In this research, graphene-copper (G-Cu) composites were synthesized via hydrothermal method, using glucose as catalyst, with 5, 15 and 25 wt% copper compositions. In this paper, G-Cu composite is synthesized with different wt% ratio and were characterized using scanning electron microscope (SEM), X-ray diffractometer (XRD) and ultraviolet–visible spectroscopy (UV-Vis). Elastic/plastic alloy was formed by carbon and copper around 2θ = 44°. The grain sizes were observed to decrease proportionally with increasing temperature. The effect of composition fluctuates the XRD intensity peaks. The band gaps for 5 wt% (as-grown) reduced as temperature increases. Short calcination duration of the composites is observed to have reduced band gaps value to that of longer duration. The thermal treatment of (G-Cu) is observed to cause thermal exfoliation and elastic/plastic alloy formation by Cu and amorphous carbon.