In this study, we have prepared a composite adsorbent with highly dispersed Mn and Ag nanocatalyst on the surface of activated carbon (AC) by applying the Radio-Frequency (RF) thermal plasma technique for the efficient removal of VOCs. The ACs before and after metal impregnation with RF plasma treatment were characterized by SEM, TEM, EDS, and nitrogen adsorption analysis. Adsorption behaviors of toluene, acetaldehyde, and formaldehyde on ACs before and after modification were also investigated in fixed-bed systems. The experimental adsorption results for VOCs on parent ACs and metal impregnated ACs (Mn-AC and Mn/Ag-AC) were well explained by modified continuous sigmoidal (MCS) model.