Thermophysical investigations in binary liquid mixtures are important for many technological and environmental applications of exfoliated graphite nanostructures. The densities, speeds of sound, and refractive indices for the binary liquid mixture environments of water +exfoliated graphite nanoplatelets, and water +activated carbon have been measured versus composition, at different temperatures, at atmospheric pressure. The thermophysical properties such as the acoustic impedance, isentropic compressibility, specific refraction, space-filling factor, and relaxation strength have been evaluated over the composition range up to 100 kg m(-3), based on the experimental data. The absolute average percentage deviations of the calculated thermophysical properties in both systems were computed. The obtained results are discussed and interpreted in terms of molecular interactions and structural changes of these carbon-based nanomaterials.