The storage capacity of carbon fullerenes with confined methane molecules was investigated by means of DFT. Based on our calculations; C-60 and C-84 fullerenes with one methane molecule can form a stable complex. The binding energy of C-60@1CH(4) and C-84@1CH(4) was negative and equals to-0.638 eV and -0.5593 eV, respectively. C-180 with twelve confined methane molecules has a stable structure. However, C-180 tends to store just six methane molecules and the binding energy for the 6CH(4)@C-180 complex was minimal (-0.256 eV). Regarding obtained results on the electronic properties, the values of the energy gap for 1CH(4)@C-60, 1CH(4)@C-84 and 6CH(4)@C-180 complexes were 1.1 eV, 0.87 eV and 0.94 eV, respectively. We have also studied the mechanical properties of C-60, C-84, 1CH(4)@C-6(0) and 6CH(4)@C-180 by the use of DFT and experimental procedure. Moreover, the stability of 1CH(4)@C-60 and 6CH(4)@C-180 complexes was studied in the temperature range between 300 K and 1200 K. We found that the complex structures were slightly distorted and the values of Young's modulus of them with increasing in the temperature value decreased significantly. (C) 2018 Elsevier B.V. All rights reserved.