Geopolymer/activated carbon composite materials were successfully prepared using alkaline activator solution to be a binder. The physical and mechanical properties of as-prepared samples were characterized through X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrometry and compressive strength techniques. Results revealed that geopolymer/activated carbon composite materials exhibited amorphous phase and spherical-like and plate-like morphologies. Fourier transform infrared spectrometry results indicated that after the geopolymerization reaction, the band at 977 cm^-1 was shifted to lower wavenumber (975 cm^-1). This might be attributed to the interaction of aluminum atoms and the formation of higher cross-linking in silicate geopolymer structure. The compressive strength of geopolymer/activated carbon composite materials decreased with increasing amount of activated carbon in geopolymer. It was found that the concentration of 0.001 mol. % activated carbon introduced into geopolymer gave the highest strength compared with other samples.