Introduction Many features, emerging from mathematical techniques, have been used in the analysis of brain signals. In this study, the physical quantity of “moment of inertia” (MOI) was introduced as a feature to enhance high-frequency waves (HFWs) in electroencephalography (EEG). Materials and Methods In this research, the recorded EEGs from F3, F4, and Cz points in 20 males were used. A total of 30 noiseless epochs (4 sec with a 1 sec overlap) were selected for each eyes-open and eyes-closed state from each brain signal. After averaging the relative power spectrum (RPS) of 30 epochs and obtaining an RPS with low fluctuation, the MOIs of the power spectrum and each EEG band were calculated. Results The MOI enhanced the HFWs of brain signals; therefore, HFW fluctuations in the power spectrum of MOI were more evaluable and observable than those of RPS. Paired t-test showed no significant difference in the asymmetry of MOI between the eyes-open and eyes-closed states (P=0.227), while the MOIs of alpha and beta bands between these two states were significantly different [F(1, 38)=11.8; P=0.001 and F(1, 38)=12.9; P=0.001, respectively]. Conclusion This study demonstrated that the MOI of different frequency bands might be used as a feature for some patients who are different from healthy subjects in terms of high-frequency bands or performance of two hemispheres. Therefore, in order to ensure the applicability of the obtained results, evaluation of MOI for EEG of some disorders, such as attention-deficit hyperactivity disorder, alcoholism, and autism is suggested in future studies.