© 2017 Elsevier Inc.In this study, a mordenite-rich tuff (M) from the Şile region (NW Turkey) was treated with HNO3and H2SO4at various concentrations (1.0, 3.0 and 5.0 M) at 80 °C for 3 h. The adsorption properties of ethylene (C2H4) and hydrogen (H2) on natural and that of acid forms were examined experimentally at 273 and 77 K and up to 100 kPa using volumetric instrument, respectively. All the samples were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), and nitrogen (N2) adsorption methods. Some differences on XRD pattern were signed in between natural and acid modified samples according to the intensity, sharpness and crystallite degree of mordenite peaks. C2H4and H2adsorption capacities of the original and acid treated mordenites were in the range of 0.762–0.876 mmol g−1and 1.373–1.672 mmol g−1at 273 and 77 K, respectively. The increasing retention values of C2H4and H2after the acid treatments were analyzed in comparison with the structural changes.